I'm 17 and started sexual relationship recently. We always use condom, but I'm still thinking of taking birth control pills. My period should have started 5 days ago, but it didn't, and I'm not sure if it is ok, because I sometimes have 2-3 days delay and sometimes it starts earlier. I hope this is not pregnancy, so if it isn't I think it's worth to start taking pills, but is it okay to start at such young age?