I'm scared i might be pregnant.. :/

My boyfriend and I had sex, and he thinks some might have came into me. My period was missed for two days, and its always been on the dot kinda thing, and, I was suppose to start it the 24th, I started the 26th, and I had little cramping the first day, but after i had no cramps at all. I am on a "like" period thing. Like.. I had my period, its 60% brown, 40% redish-pink. It also doesnt come out, the blood, when I pee, and i only know when I take out the tampon(which I kinda put in there half and half because I dont know what its going to do. And i start at the beginning of the morning but by mid day, its all gone, no more bleeding. and its been like this for at least 2 days now. And I have been also feeling kinda sick when i stand up at random times, and I have soft breasts, and they get tender at random times. and my stomach hurts, also, at times, and I get hungry at times too.
I took a test, it said negative, butttt I was on the period thing. So i have no idea...
If someone can help me out, or experienced this, can you talk to me?
I had my period last month, if I am, this is month one.