Confused

1) Don't do it. No one has the right to demand you change your body. Its your body, and you have exclusive rights to mess with it. That your girlfriend is asking you to do this is something of an alarm bell to me.
2) No such pills exist. Even testosterone doesn't have a significant effect.

 

Tell her no. She needs to love you and not want to change you.

 

I can hardly hear you over the alarm bells.

 

Don't do it! She has to accept you the way you are!

 

I know the feeling when you'd do anything to please someone and its hardnto tell them no but if it's something you're not comfortable with then don't do it.
It won't help you or her or your relationship and could end up with you resenting her too.