Could I still be pregnant? please help !?

My boyfriend and I had unprotected on February 6th. on Feb 14th, I had dark spotting, but it was so light, and was only visible when I wiped. It only lasted that day, wore a pantyliner and the spotting didnt appear on it at all. I am very nauseous lately, like all day, it comes and goes, and i have a pain on my lower right abdomen, it feels like a cramp. My lower back has some pain sometimes, but that comes and goes as well. I have been urinating more frequently. I have been feeling extra tired, and my boyfriend said im super moody lately. More so than usual. Thursday I bought a pregnancy test and it was negative. Could it be too early? please help me. Im supposed to get my period on feb 21st. Last time i got it was January 24th. But I wouldnt think that it would be negative if I was pregnant. Also, yesterday I was in the car with my boyfriend, I was in the penger seat, and all of a sudden I felt wicked nauseous, i put the seat down for a little bit and i felt better like 10 minutes later, but it was bad. What should I do?? Any opinions. PS. I dont want an abortion if I am, i would love to be pregnant, i just want to know people's opinions. I am very forgetful lately and a co worker at work said she was the same way before she found out.