am i pregnant

my husband and i have been trying to have a baby. i had some break through spotting 8 days after ovulation. my period is normally extremely heavy for 7 days and i spot for 4 days prior. well i started to spot for 4 days but it was very light normally spotting takes up the whole mini pad and this time it was just a spot or small line. this has been going on for 4 days and all the pregnancy tests are negative. i am going to call my doctor on monday, my breasts are tender and certain foods make me gag but no throw up. could i be pregnant or is it just in my head?