Calendula

As a token of encouragement (for you to acquire the relevant evidence to support your future B1/B2 application), did you know that you'll actually get a passport stamp at your point-of-entry for a visit up to 6 months each time if you are travelling with an approved B1/B2?   
 
But for now, I can't stress enough that you need to work on what all of us have mentioned in this thread. I personally want nothing more than seeing you achieve your objective in obtaining a B1/B2 and spend more quality time with your bf and his family and friends. 
 
Chin up, think happy thoughts, plan the appropriate steps accordingly and go get 'em! Perhaps your bf could visit you in France! Best of luck 

I can imagine how hard it is.
I'm originally from Germany and when I visited my boyfriend in the US I only had a part time job...so I totally understand how frustrating it can be if you want to see the person you love but cannot really afford it to be with this person.
I did stay for only 3 weeks, so ESTA was the document to go with.

@Calendula My fiance and I are still waiting for our I-129F NOA2 so I understand how you feel about long distance. We literally voice and video call on a daily basis
 
With you having a ESTA, it's a lot easier for you to make a trip whenever possible so look at the bright side. You're a young graduate so go out and get some work experience in France to work on your financials at the same time. Besides, having work experience might help with your job hunt in the US.

You just type @ followed by the username
 
And yes, it is generally difficult for a I-129F beneficiary/K-1 applicant to get a tourist visa. Reason being, you already have immigration intent. Under such circumstances, no matter how strong your ties are in France, it will no longer help much.

As others have mentioned, based on your lack of solid ties to France, you are much better off sticking with the VWP. Also your recent 3 month trip last Sept may play a role if you attempt to enter the US too soon. It will look like you are living in the US with your bf rather than visiting. Also keep in mind that legitimately any travel and meeting of new people can be accomplished in the 3 months given. There really isn't much that can't be accomplished in 3 months, not to mention most people can't afford a stay of 6 months on their own or be away from work that long either. Much fewer hurdles with the VWP.