Please Help. Might be pregnant at 16

I am 16 years old. Me and my boyfriend had unprotected sex 3 times on the same day which was on the 28th of August. And I was supposed to ovulate 2 days after that. I had my period on the 14th of September, but usually my period lasts 6 days and very heavy but this time it only lasted 4 days and very light. I would usually have to use tampons and change them like 6+ times a day but this time I only had to use a pad and change it once a day. I have been having cramps, feeling tired, back pains, shock/tingaling sensation in my breasts , feeling like going to throw up but dont. Please I really need your help I have no one else to ask for advice. I dont know if Im pregnant or not. Please Help…..!!!!