Sex too soon?

I'm 18 and I've dated a lot of boys. I never slept with any of them except my current boyfriend. We were best friends for a year before we dated then we were exclusive and  were in love for two months and then I gave him my virginity. My best friend is always talking shit to me saying that's way too soon and that she thinks I'm not mature enough to handle sex if I give it up that fast. But I've had many boyfriends and never had sex! And I had known my boyfriend has a friend for a year and I knew I wanted to give it to him! Was it too soon? Or what should I say to her next time she mentions it ?