Im 16 years old and a couple months ago my period just started to regulate to every month instead of every two months. When I was in gymnastics at 12 years old my period stopped completely and I had it seemingly every time I took a break from the sport. Now I'm in swimmimg practicing vigorously for two hours each day. I am not sexually active even though the head of my boyfriends penis once barely entered my vagina, but I gave him oral sex beforehand, for which he never ejaculated. I was supposed to start my period either today or tomorrow and normally I start a couple days before I'm supposed to menstrate according to my calendar. I usually spot a bit before I menstrate but this time I spotted for a couple days and then it just stopped. There have been no spotting or bleeding at all since then. Could my active sports be delaying my period again, or could I be pregnant?

You could be pregnant but its not likely if you think you are you can buy a pregnancy test very easily, the reason you could be pregnant is because even if he didn't ejaculate there is something called prejaculate which does have enough sperm in it to get you pregnant because it doesn't take much. It could be the activity you are doing for whatever reason when you burn to many calories your body stops or slows down bleeding.

And also I for got to mention your boyfriend obviously know when he comes but pre comes out with out notice when he is aroused