I am a 19 year old and I had all three Hpv shots in 2010. at first my period will come every two months. but as time went by it went from two months to every five months. I usually get it at the end of the month but when its around that time I will feel the cramps but nothing happens. I haven't had my period since 2014 to now there is still nothing happening. please tell me what's going on I'm getting a little worried.