Opinions?

So, I'm 16. I'm on the pill, I haven't missed any or anything, but I was supposed to get my period two days ago, and it hasn't come yet. I'm actually seriously worried because I am so not okay to be pregnant. Especially because the guy who would have impregnated me is my ex, and we have a friends with benefits type of relationship and so yeah. It would be really really bad. I need advice. Thank you!