what can i do

when my daughter was 1 1/2 i gave her up to my mother who was supposed to take care of her while i was unable. i had ppd which came later in her infancy and that caused my bi polar to pop up in a bad way. while my mom was taking care of my daughter she convinced me that the only way that she was able to fully care for my daughter was if i signed adoption papers to give her up to my mother and step father. i signed papers because of course i wanted to do the best thing for my daughter and at that point i was in no shape to even care for myself with my mental state. well time passed and after i had my life and emotional state in check i came back to my mom and said ok i'm ready to get my child back with me, nothing..... my mom told me that i can't have her at all now. the deal we worked out before was that until i could get my life and everything in order she was care for her and once everything was ready i would have my daughter back. now she's saying that there's no way that i'm getting her back at all. i know at the present time that my mom has been abusing behavioral medications and tells people all the time that she can't handle taking care of my daughter but won't give her back to me still. the very first reason that i had for giving my child up was that i felt like i wanted to kill myself and didn't want her there if i couldn't control myself and a couple years back now my mom tried to kill herself and my daughter found her bleeding and all. i know that at this point my daughter would be way better off with me than in her situation with my parents. about a month ago i told my mom that when my daughter is old enough to understand i am going to explain the entire process and why i gave her up in the first place and why she isn't with me today which i still feel is my mom just being selfish and not wanting to give her back anymore. my mom hasn't talked to me since then. i'm pregnant right now and keeping this child and i don't know how my daughter is going to feel about it or if my mom is going to tell her nasty things about me not wanting her but wanting this baby.....i don't know what i can do about this stuff anymore........sorry if this was jumbled and confusing but basically what could i do possibly to get my child back if i already signed papers a few years ago