Confuse???

I don't know how this conciveing thing works. But I had unprotected sex around Nov. 7, three or four days before my period ended. Three weeks later, I begin to crave for some chocolate milk out of the blue every day . The next day I begin to us the bathroom less then ten minutes. My boyfriend begin to notice that I have been using the bathroom. We had sex after that I didn't feel too good like I wanted to vomit (which I did). The next day same thing again but I begin to feel more tired and sleepy. I had to stop drinking chocolate milk because it keeps making me vomiting I don't know how even though I still wanted some chocolate milk. I took a pregnancy test it says I'm negative. My period had suppose to come on the 18th or 19th of this month but it came on the 24th which is odd for me, that never happen to me before. My period always be on the right date when it's suppose to come on. I don't have any major cramps at all. My period is about to go off and I'm still doing the same thing, peeing less then ten mintues, feeling tired everytime. I still crave for chocolate milk even though I get a bit nauseous. I don't know I'm confused already just by telling it. Maybe it's just in my head 😞😞😞