Hello. I am an 18 year old cheerleader. I haven't seen my period since late October last year. Since then, I had protected sex once. The condom didnt burst or anything and I took two pregnancy tests that came out negative. Also, since October I had two serious falls on my back due to cheerleading and a chest infection. I was given two different sets of medication for these incidents. I'm a bit worried as to why my period is so late. Any advice?