Helpppp meeeeeee

Hi, I had unprotected sex he didn't cum in me, it was only a couple of seconds (3 seconds most likely)  and I got my period a couple weeks after, it was heavy and a little bit clotty, this was almost a month ago when I got my period. 
But I've been having this bloated/gassy/and and have been feeling the way people get when they are about to throw up???? Is this normal?  Could I be getting my period soon? I'm irregular so 
Also, I took a test just to ease my mind. And it came out negative!?