Where is my period?

My period is usually always regular.. It would come between the 4th and 6th of every month. October 4th I had my period as usual.. no problems. A little later in the month my boyfriend and I "dry humped".. he had basketball shorts, boxer briefs on and I had shorts and a thong on.. And then I gave him oral sex.. all of which I am aware you can not get pregnant from doing.. I am a virgin. I have been under a lot of stress with school, my boyfriend and a lot of other random things going on in my life lately. November 4th..5th..6th..7th.. all came and went with no period. The entire month of November I went without a period. I had spotting around the 1st through the 4th.. but it was barely anything. My mom is a nurse and said that may have just been my period for the month.. But it is now December 7th and my period is still not here. I didn't have any cramping last month at all.. but this month I started cramping around the 4th.. they aren't very intense cramps.. just random and obviously there.. I put in a tampon thinking I was going to start on the 4th.. and when I took it out there was just a small spot of blood on it. Barely any. Freaking out I took 2 pregnancy tests last month at the end of the month.. then I took another one yesterday morning because I know first morning urine contains the most pregnancy hormone. Still negative. Am I just freaking myself out and scaring my period away? Or is there a possibility I am pregnant? I have no other signs, I am tired.. but I have been tired all semester from my lack of sleep. My breasts aren't tender at all.. I'm really bloated.. but I have colon problems so it happens a lot. The only thing different from any other time is that my stomach feels kind of uncomfortable.. especially when I try to "suck it in". But that started after I had a little too much to drink at a friends house and threw up..

I really need some relief.. my mom says my period isn't coming because I keep worrying about it. But I want to know someone elses opinion.. especially because I haven't gone into this much detail with my mom..

Thanks,
B