ISO Birth Father and his Family and Half-Sister on Birth Mom's Side

I am in search of both my birth father and his family and my half-sister on my mom's side. I was born on June 29th, 1988 in Atlanta, GA My mom's name was Donna Rae Johnson, she was born on March 31, 1967 and originally lived in Reno, Nevada but moved to Georgia in 1982-3 Where my sister (whose name at birth was Jessica) was born on June 15th, 1984 (approx.) I am also in search of my birth father and any of his family. Sadly, I know nothing of him other than my mom had said he was possibly of Italian decent and that he had been with her in Sept-Oct of 1987 This is made hard because my adoptive dad signed as my biological father on my birth cert. even though he was not my biological father... If anyone can help, give me advice or know anyone that relates to them in some way, shape or form, please let me know. I am really running out of options.