Please help, only 16!

I've stupidly been having unprotected sex for atleast two years now (with the same person) but it's only just dawned on me that I have never got pregnant. My mind just wasn't focused on that and I was way too busy with other things. I am going to get birth control now but I do want a family some time and I'm worried that there is actually something wrong with me or is there a reason why I may not have got pregnant yet? Any suggestions?