Am I Or Am I Not?

Me and my husband tried for a baby during the time I was highly fertile (october 1st was accidental, october 2nd and 3rd was on purpose). I took a pregnancy test on the 15th at night before going to bed, and it said negative (i also took one on the 5th and 12th of october, just because I was anxious to know, but they were too early to tell, so therefore, were also both negative). During those 2 weeks that I was waiting, I did have breast soreness, and I drank a lot of water, therefore, made constant trips to the bathroom. I did feel dizzy at times and had waves of nausea coming and going. I am a massage therapist, so most smells I usually could stand made me sick to my stomach. Now, this might of been just because I was anxious to get pregnant, and my mind was making up symptoms. But for the past couple of days i've been getting these waves of cramps and my stomach feels tighter then before. I did get my period on the 17th of october, and it was light at first. Then that same day I got a massage (because my muscles were sore) and afterwards it got heavier, but for only 3-4 days, then for the remainder of my period (which was another 4-5 days) was just drops of dark blood followed by gray mucus/discharge. Today I got this terrible migraine (at 11pm) along with nausea, but didn't throw up. I don't have breast soreness, and I do take my over-the-counter prenatal pills (since I heard that it's better when you take then before you try to conceive), so you're less likely to get sick during your first trimester, and it helps having all the folic acid.
Could I still be pregnant and not knowing it? Or did my period basically said it all (not prego)? Should I still go to my ob/gyn and ask for a blood test instead of getting another hpt test?