Am i pregnant and don't know it?

I'm 16 and i had protected either in march or april of this year. we did not finish though. im also on BC. i can't remember the last time i had a period. I have not gained any weight im still like 106. lately i have been feeling what seems like menstrual cramps but i never get my period after. today i felt something that seemed really tight in my stomach i dont know any other way to describe the feeling. i havent really had any pregnancy symptoms. now that i think about i threw up one morning after i took some pain reliever and after i ate a muffin and a couple days after that i felt really nauseated like i was gonna get sick but never did. Ive watched those shows and thats what made me think of this. I want hot cheetos all the time but i liked them before too. what do you think