How can I find out who has custody over my son? Me? The Father? Or the fathers grandma?

Okay, this is a pretty long story so here goes. I live in Georgia, and i had a son. I clearly had post partum depression, so i was still shocked that i had a baby. When he was born, and me and the father and child were in a outpatient room together, i got really depressed and went in the bathroom and started crying. The doctor asked if i was depressed and i said yes, so they sent in someone to talk to, but i was so paranoid that i thought it was a case worker to take my child away, so then she really called the social worker in. They didnt really tell me anything (at least i dont remember) but I do remember signing my rights away. i dont know if it was temporary, or permenant. The paper went over to the dad and the dads grandma, and they never gave me a copy of the paper, so i dont know if i have custody of my son or not. Plus they said i wasnt allowed to be around my son alone. How do i find out if i have any custody over my son? We didnt go to court or anything. Sometimes social workers would come over where i was living at the time which was the fathers and his grandmas place.