pregnant??

Sarah • college student, in love with an amazing man, just working through life.
So I'm on the pill and my boyfriend and I had sex like two weeks ago about 3 times, he came in me 2 of those times. 
My average cycle is 28 days, we had sex on day 12, 14, and 16. I'm on day 31.  
Well usually my period is like clock work and comes on the second day of my sugar pills, its day 4 and still nothing. If anything I'm having a lot of clear to white discharge. I'm super gassy. 
I took a test a day ago and it came out negative. But still no signs of bleeding or period. 
Could I be pregnant?