Can Being Overweight And Stress Cause Delay In Period?

im 17, and i rarely have sex. but the last time i did was the end of april, with protection. he didnt ejaculate until after he pulle out like 1/2mins, and the condom broke after he pulled out. i missed my period in may, but at the end of the month i took a test & it came back negative. my urine turned a neon-yellow color but i had started taking some new vitamins. i am a little overweight, and i had just gained some befor my missed peeiod. also, i had been stressing alot. my period came this month, its still here. but now its as if i can feel a heartbeat in my stomach. whats wrong with me?!