oasis1701

Do you have someone who can help you fill out the forms and make sure no fields are accidentally skipped? While the forms are fillable PDFs, I don't think that they are very screen reader accessible, so it might be good to have some help just so you know the forms are filled out correctly. That doesn't necessarily need to be an attorney though, it can be anyone you trust. 

Well for financial reasons with the cost of a lawyer, we opted instead of using a company that helped us fill our all our forms and also reviewed them for accuracy as well as all the content to assure at least from the submission point of view all was ok.  These companies are far cheaper than an attorney and I have seen reviews on them that are from the no good to the excellent.  I can only speak to my experience with them for our K-1, Adjustment of Status and CR1. They did a great job on all three instances and I never received a ROE.  You may want to look them over.

On one occasion I helped friends now they were not blind but had not paid attention to what they were doing.
 
I think if you have someone who is meticulous to help you you do not need a lawyer
 
Might need a joint sponsor 

Using a service is less costly, no issues with your documents. At least I have not heard of that complaint on here before. 
As mentioned already this is a DIY site and if you feel your reading programs are spot on I would do it yourself.
Regardless of a lawyer or a service you still need to check things and be on top of your process. Both lawyers and some services have screwed things up on ppl. You need to be 100% on top of it. None of the others will care as much as you. 

When you get to the interview stage, you’ll be able to ask for any type of accommodation you need related to being blind.   I don’t think it’s relevant to the petition stage.
 
Using a visa service or attorney will not cause extra time for your overall case, but being from Iran is very likely to, especially with only one visit.
 
International relationships are very expensive.   

This is a DIY site.  The overwhelming majority here have done it successfully themselves.

Since I do not know how well those reading softwares are at being accurate. You can always test them out using the guides here on VisaJourney and having someone you can trust go over the forms and see if they match to what the software says. 
 
The other option is to use a service rather than a lawyer. Visajourney has a list of affiliates under the tab Ask a Pro. 

Welcome to the forum.
 
Most of us here have done the process without an attorney but we also put a lot of time into research to file correctly.
 
While relationship evidence can be beneficial for certain applicants who will be going through what we call “tough consulates”, it is not what the I-129f will be adjudicated upon. It’s the evidence of physically meeting within the last 2 years before filing the petition. To clarify, you did meet in April in person and if so, can you present evidence of that such as boarding passes and passport stamps? 
 
The best thing to do is familiarize yourself with the instruction to I-129f, it’s a separate document and can be found on USCIS.gov.