Have you guys been seeing a marriage counselor? It might help you both see what positives and negatives your doing with each other that you might not even be noticing. Personally I think marriage counseling is great because you don't have to be in trouble to be able to learn something and strengthen your marriage.

Something I noticed though ... you said she's been through quite a bit that you thought would mature her. Often times, past trauma can cause someone to feel poorly about themselves, even if it isn't readily apparent. Because of this, they can subconsciously sabotage themselves like overdoing things, having trouble dealing with responsibilities, etc. She might want to really look closely at these things and talk with her therapist and in marriage counseling as well about them.