could i actually be pregnant or is it something else?

my boyfriend and i recently got into a bad habit of not useing condoms.. im on birth control but i had missed a few pills here and there this month. He has pulled out but I know theres always a chance of him not pulling out in time or even pre cum... well all last week i had basically no appetite I wouldnt throw up but i couldnt smell food or even eat food 99.9% of the time.. then a few days later i started to get lightheaded and dizzy and sometimes i get to the point where i feel like im going to pass out... my back has had some pain ... I took a pregnancy test but it came out negative... my period will should come sometime next week so i know that its possible that i took the test too early.. I have had some spotting last week.. and i ended up in the er a few nights ago they did ask if i had any chance of being pregnant and i shouldnt have said it but i said no bc my aunt was in the room and i didnt want her to know even though im 19... but i assume that since they take blood and urine labs they would automatically check for pregnancy?....am i wrong? but they basically said i was dehydrated and its probably stress.. but im not under stress... now it seems like im feeling bloated and ive been haveing mild cramping but my period wont be here till next week... I also feel like i have to go to the bathroom alot today but when i go i dont even pee alot... if they did test for pregnancy at the hosptial could it have been too soon? and could it be wrong?... I cant wait till this week to see if i get my period or not .. I have one home pregnancy test left but im afraid of taking it too early... whats your opinion? please help!!!