I'm going to subtly pressure my gf to have sex because I felt pressured to have sex
What did you feel pressured to do?
I felt like if I'm not ready for sex I will fall behind my friends
I remember what peer pressure was like as a teen.   You should base whether or not to have sex on whether you are both ready to do it.  Not doing so could end the relationship and cause regret from both of you.
But I want to fit in with all my friends.
I understand wanting to fit in but you can fit in and also not get pressured in to things you aren't ready for.