mam521

If you have an unexpired Green Card, just get on a plane and return to the US....now.

That depends on if a 221g form was given to her after the interview.  My only thought is she has to make sure the CO did not provide anything that may have asked for more evidence, or a needed clarification.

If they returned her passport, she didn't pass.  They're probably going to ask for more information.  When they get that, then they might decide.

I agree with @carmel34, if marriage is the plan, then maybe it is time to work toward that and the eventual spousal visa.  Your most recent stays, and withdraw request for admittance should not impact that visa although there may be questions.  You might be able to visit again during the processing of the spousal visa petition after a suitable time outside the US (6-12 months), and with work ties to Canada, but as @Ontarkie mentioned, you are flagged, so who knows if CBP will be convinced.
 
Good Luck!

Best path forward is for your US citizen boyfriend to visit you in Canada, get married, then he returns and files an I-130 petition for you after he has the marriage certificate.  Another option is to get married online via Utah County, then after he visits you in Canada he can file the petition with the Utah marriage certificate, which may be faster depending on the province in Canada--some take many weeks to issue the marriage certificate.  You can try visiting the US again, but since you have been flagged already on your most recent attempt and denial of entry, it would be better if he visits you in Canada during the CR-1 process, which will take about two years from the date of filing the petition.  Your denial of entry will not affect your CR-1 visa process.  Good luck!

You were rightly denied entry because you were de facto trying to live in the US on a nonimmigrant status.  Going forward, you should plan to use the entry privilege more like a proper tourist, for reasonable periods of time.

It would depend on the visa. Not likely but one can never be sure.

When you were turned around. Those notes are in the system and will be for a very long time. It is recorded that you withdrew your request to enter. That is a sign that they did not believe you were just a tourist. 

No overstay, but you are now flagged.

What @Boiler is saying is that there's no chance of them getting B-2. This is what I also wanted to say when I  asked you if you're familiar with "Bogota and B-2s"
 
Colombians are notorious for overstaying in US. As of today, Mexico has put a strict measure on them because they're now using Mexico as a catapult to get into US via border and claim frivolous asylum. A lot of them are being denied/ being deported as soon as they land in Mexico. There was such a post here a month ago. 
 
 

Boiler isn't my 'buddy', I don't know him, he's a random stranger on the internet. But personally I think your posts to him have been ruder than vice versa. I suspect the link about the wait times was simply a 'just in case you're not aware, this is how long the wait times are' - you'd be amazed how many people wouldn't know that there is a potential 2 year wait for an appointment and would think their relative would be over for a visit next month. 
 
As for you being in the US meaning that your relatives visas are less likely to be approved, just have a hunt around the forum and see how many people have been refused B visas for suspected immigrant intent, or lack of ties to their home countries. Having you in the US makes that much more likely. 
 
And yes, I agree that somebody not submitting their own application is fine but as you say that's for those who are illiterate or unable to complete their own applications - if that's the case then fair enough, but you haven't mentioned that being so. You completing the application for them if they were able to do so themselves just emphasises their tie to you which may not work in their favour. But this is all a guessing game, nobody knows for sure what will happen. My guess is that they will be refused a visa, as they have pretty much everything against them - US family, no money/resources, being from a high refusal country anyway, etc. But until they actually go for that interview, there's no way of knowing and sometimes there have been cases where people have surprised us and been given visas despite their circumstances.  I wish them the best of luck. 

B-2 tourist visa applications and interviews assume immigrant intent, which must be overcome by the applicant.  The stronger their ties to their home country (good long-term stable job/income, property owned, etc.) the more likely that they will be approved.  Each adult applicant will be considered separately and has their own interview.  Having relatives in the US weakens the ties to their home country, and increases the likelihood of overstaying in the US as many have done this before.  Another piece of evidence showing weak ties to Colombia and stronger ties to the US is the fact that you are paying for everything.  No one here can predict with certainty how this will turn out, all they can do is apply, interview, and hope for the best.

They may suspect (also as evidenced by your inquiry here) that you will not return to your country.

Since her husband is not present, she will require the listed father to fill out a completed DS-3053 form and have it notarized.  
 
Also note, she will have to take the baby to the Passport Office for the appointment.  

Beneficiary's job status isn't a big deal.  The petitioner's is because they (or whomever is listed as the financial sponsor on the I-864) are the ones financially responsible for the immigrant when they move to the US.  

Have you been keeping an eye on your junk mail for this request?  Was there any mention of what it is, like a DS-5535 form to fill out with your 15 year travel history?  
 
Your visa will be valid for 6 months from the date of your medical or 6 months from the issuance of your visa, whichever expires first.  Your case will be your medical expires sooner.  The consulate will not extend the validity of this visa.  You will have to try and get it reprinted if you don't enter the US before it expires.  Additionally, your child will require proper documentation to enter the US as well, be it a CRBA and US passport or their own IR-2 visa, if you enter after their birth.  

Just let your bank know that you are making a payment to USCIS so they don't try to block it!  

A-number and USCIS account umber are two very different things. All immigrants have an A-number. Only those who have previously filed a petition ONLINE have a USCIS account number. Many of us never filed a petition online because the petitions were paper filings only back then, so we don't have any such numbers. You will get one after you have submitted your online filing, so you just skip that question when you fill out your petition. 
 

Retirement savings and life insurance plans - putting each other as the beneficiaries, if you want another strong evidence. But, sounds like you've got it pretty solid as is.  

You're solid then. 

The law officially got announced today, will go into effect 6/26/24!

File at the end of March.  You'll pay the smaller fees.  It's just the filing, so until you have an interview and an oath, it's just that - an application.  Chances are it will take a month or 2 before your case would be eligible for an interview, so hopefully the law will have passed.  Even if you've passed your interview, you still have to have your naturalization ceremony to actually become a US citizen and that oath ceremony could potentially be rescheduled/delayed.  As long as German parliament pushes the actual changes into effect in mid-April as anticipate, you should be good to go.  

If you are petitioning him as a spouse of a US citizen (CR/IR-1) then only your husband will have to complete an interview at the consulate in DR. 

Iguazu is bucket list!  I have an Argentinian friend and colleague who's never been.  I told her we will go together  

Not for this section, but in general he should attach all the bonafide marriage evidence for his N-400 based on marriage: joint taxes, joint account bank statements etc etc