How can I change my daughters name to mine,the father, in Ga?

My Daughter is now 11 and has been toting this name around with her the entire time and wants in GONE. I cannot get any help from the courthouse, they just say there are forms, but we cannot tell you what they are or how to get them. I have asked an attorney and they want 400-500 dollars before they will even start which is ridiculous. This should have been done when I was legitimizred. I had to go thru a DNA Test, then legitamation and then still took me 8 months to get her finally home with me. I do not understand the court system nowadays. The mother developed a Drug Habit after we started seeing each other and I found out and gave her an option to fix herself and she didnt so we split, but not before she was pregnant. The whole time I was told it wasnt my child, so the day she was born I called and started the procees of having this all taken care of and within 4-6 weeks It was a fact that she was mine. Now why wasnt that child sent home with her father after it was a fact that she was mine. Instead she was left for 8 more months where me and my family went every monday for 1 hour and got to see her. I had some major surgerys during this and still there was always somebody there to see our child. The courts come to the that I was part of the problem for some reason and then wouldnt award me custody, but they would my parents. I of course allowed that as soon as it was even offered. Nobody on the other side of the family ever visited her while in foster care, or even tried to do anything. She really is a miracle that she made it thru the addiction that the lady that gave birth to her put her thru. Which from my understanding was anywhere from 500 to 1000 milligrams of oxcycontin a day and no telling how many xanax. But she is Healthy and doing great. Now if someone would Please help Me figure out how to get this childs name changed because it really is a part of her life that needs to be forgoton and this is tailing along with her..Any help would be very greatful. THX