A lawyer cannot help influence a consular decision on a B2 case. By law, the consulate is required to assume immigrant intent, and your bf fits the description of someone who is likely to overstay that visa, hence the advice you’re getting about lowering your expectations.
There is no financial sponsorship or affidavit of support for B visas. If your mom won’t let you go there to meet, you may need to wait a few years until he can get a B visa.