Period and Cramps, can i still be pregnant?

Usually my boyfriend and I have sex with a condom. One day, it broke and I started freaking out so he bought me the morning after pill, which wasn't bad because they're so small. I got my period (or what I think to be my period) but it was lighter then usually, but  that was one of the side effects. I not being satisfied, I continued to look up if there was a possibility if I could still be pregnant. I found out you can be pregnant and continue to have your period, but it only happens to a few people and seemed to run in peoples family. In my case it doesn't. 

That was in May. Recently, my boyfriend and I still continue to use condoms, but a couple of times he would stick his penis in for only a few seconds and then pull out. No ejaculation. I again, freaked out and did research and learned you can get pregnant from precum but it is an extremely low chance. I recently took a pregnancy test on Friday (three days after my missed period) and it came back negative. Today, I have gotten my period, or what I believe to be my period, but its a little lighter then usual. I don't believe I'm pregnant but I will not stop researching until i know the answer for sure. 

My question to you all is, what is your  opinion? Do you think I'm pregnant even though I have gotten my period? My period also always comes with extremely bad cramps, which happened everytime i have gotten my period. My boyfriend doesn't believe I am, neither does the clinic or the Planned Parenthood operators. But I won't stop until I get more opinions (and when I take another pregnancy test).

Thanks everyone.

PS. I haven't really had any pregnancy symptoms, only a little tenderness in the breasts and a little cramping but that could be because it was before i was starting my period.