This sounds like a really awful situation and I can imagine just how worried you are.
Option a) is probably the best one because you wouldn't have to disclose that you hadn't been paying pension contributions and your new employer wouldn't have to provide the DRV with any information about your previous employment either.
If you are based in the Munich area, I could give you the name of a very good social insurance lawyer who wouldn't charge an arm and a leg for some professional advice - and he may even be able to help you if he doesn't have to represent you in court in another part of Germany.
The lawyer's email address is:
Jens is specialised in social insurance law and has helped many freelance English teachers here.