Pregnant ?

I'm sorry I may sound very uneducated about this because I am, but my boyfriend, well technically ex, came in me about two weeks ago and I took a plan b, but took it about two days later. Then he came in me again a couple days ago and I took a pregnancy test the next day and it was negative. Now today I thought i started my period but the blood was more pink than red and it is very very light which is not normal for my first day. Anybody got any advice on what might be going on ?

ps don't need a speech about how I should be using protection if I'm not on birth control, I know this. Our relationship is complicated but that part really isn't your business