???? uh could I be pregnant ????

So me and my boyfriend had a lot of sex the 8th and 10th of this month. We didn't use any protection and I noticed last week that those days we had sex was when I was fertile.
I've been feeling extra tired and sleepy lately, sleep is all I look forward to now. I feel nauseous most of the time as well but I don't ever throw up.. Speaking of nauseous, I feel like throwing up whenever I smoke cigarettes now and that's never happened before. I usually smoke up to a pack a day but now I can't because it's gross to me now. I've also been having lower back pain out of no where. And my boobs feel EXTRA heavy. Could these be any symptoms?
Anyways, my period was supposed to come on Wednesday and it hasn't. My period is ALWAYS on time. I tested when I came home from work and got a negative result that day but my mom told me to wait until next week to test again because she thinks it could be a false negative.
Any suggestions?!