Okay. I'm 16 years old and I've had irregular periods for a while. It's not unusual for me to have a really heavy period one month, and then barely have one at all the next month.. and they don't always come at the same time. I recently, about 2 months ago, became sexually active for the first time. The last time I had sex was June 30th. My period last month was extremely heavy. It came on the 9th of June and finished about the 16th. This month, on the 5th, I just had a little bit of blood for part of a day. I've never had unprotected sex and I have only had one partner. Here it is, the 13th, and if my period was going to be on time, it's 4 days late. I'm not sure if I should worry or not. We used a condom, and I did have some blood on the 5th of July, and it's not uncommon for my period to be irregular. Can somebody please help me? Should I worry? Please.. any information is greatly appreciated.