What Causes Delayed Periods With Dizziness?

hi im 5'7 185lbs and im 21 my period is 4 days late i have 2 negative home pregnancy test but ive been feeling light headed sometimes and dizzy. it comes and goes. sometimes when i lay down i almost feel like passing out. like really bad light headedness. in February my period was late for the first time ever and i got a pap smear after 3 neg pg test. i bled during the exam and a day later started my cycle my period has been normal ever since until now of course. i dont know if i could be pregnant even though the test say negative or im having symptoms of something else. so i guess my question is could i still be pregnant even tho i took an early detection pregnancy test with morning urine. i havnt been under any stress either if thats a question .