Hi..had over 5 negative pregnancy tests and still have not recieved my period and i am over 3 weeks late.. seeing a doc friday. what could be wrong?

Get checked,,: There can be many factors why this is. It could be a condition known as polycystic ovarian diseases (pcod) where there are high levels of hormones but no ovulation and few if any periods, or it can be due to oral contraceptive use and disuse, making the period irregular, or it can be that the test kit was defective or the test was done wrong. At any rate, it's the right thing to get examined.