>>11283240Probably can't unless she's still developing. Does her mom have big boobs? If she does there's hope - if her mom is flat your SOL.
Birth control pills + gaining weight might buy you two cup sizes if your lucky. You could also knock her up.
Since transgenderism has gotten so popular there are is a surprisingly robust community that's into natural BE - herbal hormone stimulants and stuff, but the success rate of those methods are almost entirely apocryphal - they can also be harmful so it really requires full commitment from your SO.
Fun shop talk aside unless your GF is into boobs or BE don't mention this shit to her or you'll give the poor girl a complex.