could I be pregnant? please help me

So I'm 17 and I'm not a virgin but we've used condoms every time, always make sure they're not ripped, pull out and sometimes use spermicide along with that. I haven't gotten my period since the beginning of December. I have felt nauseous randomly the past couple of weeks, I'm tired constantly and extra emotional. Could be stress or overthinking but of course I'm still scared. I have taken several pregnancy tests every few days for a couple of weeks and not even a faint positive. So today I thought I for sure got my period, really bad cramps pretty moody and bleeding. The bleeding was just heavy spotting and the cramps and everything else is gone. I don't know what that was but I've heard of similar pregnancy symptoms? So I'm freaking myself out here. I told my boyfriend I got my period and I'm not pregnant but now I don't think I did get it. What could that have been and is it likely that I'm pregnant?