We don't know for fact, but husband is pretty sure that she did, looking back (meth). They were young when they "hooked up"; he didn't know her well at all. He didn't know she even had a problem until 3 months after difficult child was born, even though they lived together the majority of the pregnancy. We know that she did with her two subsequent children. By then the drug use showed badly. I'm glad you brought it up, because I am always surprised when professionals seem to place no real importance on that.
I agree that a neuropsychologist evaluation is needed badly. I am so excited to begin with this new therapist, and possibly get some referrals for that and a new psychiatrist!