Plan B pill and pregnancy?

Alright, Me and my boyfriend had sex without a condom 2 weeks ago, we didn't have full out sex without the condom, maybe for 2 minutes without a condom, then we got a condom, And after awhile we notice he wasn't coming, and thought maybe he did come, but he would of felt it so we thought chances are slim to none, and on monday we were having sex with a condom and it popped and just to be safe I took plan B, about a few hours after taking plan b I got bad cramps, and felt bloated, took advil and all was fine with the cramps, still felt bloated, for the last week maybe 5 days I've been eating a lot, Tuesday, today my breasts are feeling really sore, I still feel bloated and I'm getting randoms pain in my abdomen, are these just symptoms of plan b? also for the last week I've been constipated which I heard is a sign of pregnany, but also I've been a vegetarian for 3 years and eat a lot of cheese, and by a lot, I mean a lot, I eat a lot of pizza, grilled cheese etc, could anyone help, also I'm due for my period Thursday, exact, 28 days..I'm usually like a day early or a day late, took a pregnancy test and it came back negative, so I'm asking for your opinion, Thanks!