Im 13 and i cant remember when was the last time i had my cycle.?

I went over my nephews house over the weekend(16yrs old) and he had his hands in his pants(front area,ewww ya) I dont know if he was touching anything.So like,Im scared i might not get my cycle,i could have touched his hand and put my fingers in my mouth.Can i be pregnant for putting my hands in my mouth???! I didnt sit on his lap so it couldnt have gone through. Another question:SERIOUS! All of a sudden my stomach has gotten bigger.I dont understand whats wrong,even when I eat little meals my stomach gets bigger.My mom said you look pregnant.I REALLY NEED HELP.Please answer this question.IM REALLY AFRAID *****PLEASE RESPOND ASAP PLZ,AND PLZ TAKE THIS SERIOUS!!!****** THANKYOU IN ADVANCE :)