Sounds like you have a charlatan lawyer. A change of status (COS) from B to F1 would have been possible if you hadn't overstayed, but not now.
Also: an F1 is a non-immigrant visa, which I can't ever see you getting again with an overstay. Why would they take your word for it that you would leave after completing your education? You have violated the terms of one visa, and likely will do it again.
Are you really happy to stay here as an illegal immigrant for 20 years? Have you read about what is coming down the pike for undocumented immigrants next year? If it were me, I'd take my child and leave while I still had control over the situation.