Now she wants more custody....?

No you can not go after his money since she is not working you won't get much. What you could do is get yourself a very good lawyer. One that specializes in child custody for fathers. I think she has a good chance of getting half custody since she has been your childs life. Your best bet is keep a calendar of your childs day. If you take him to the doctors make sure it is your girlfriend but its better if you take him to the doctor and preschool. The more you do the better you look as a father. Make sure he goes to the dentist, eye doctor, and everything else. Good luck.