WOW! You're right! If I had a child at the age of 13, who had one at the age of 13, she COULD be my grandaughter! ..... 17 is legal in Georgia.
According to my calculations, you would still miserably fail the Half Your Age Plus Seven Rule in regards to a seventeen year old.
If your love interests are younger than 28 and a half years old, society reserves the right to label you a "Dirty Old Man".
You may think that is unfair and arbitrary, and maybe it is, but them's da Rules!
In fact, I'm a Dirty Old Bastard.