if you adjust to b1 you are limited to only 6 months of stay and you have to go back your country. If you maintain your F1 you are on duration of status which means as long as you enrol you are with status and apply for adjustment. Now the question is will the visa bulletin be current before the 6months max you are given with the b1 visa.

@J A my OPT is rounding up soon. I am just thinking of the fact that I have an approved I-140 and what that would mean for the approval of the B1 visa.

Highly doubtful as you have an immigrant intent. Its either you pursue another course for your F1 if your OPT is almost over or wait at your home country and do consular processing until your PD is current

As long as you have submitted your 1485 when you are still on status you are good to go. I have the same experience and after my opt my 1-485 was approved. You are good. make sure that you submit your I-485 now wiyh your I-765.