Could I be pregnant? I have been having sharp pains on my side for the last couple of hours

Only. Only you know if you could be pregnant. Sharp pains do not necessarily point to pregnancy. They could be due to excess acid production, premenstrual cramps, stomach flu, muscle pain, urinary tract infection etc. The list is very long. If you are late with your period and you have had unprotected intercourse then go ahead and take a pregnancy test. If your symptoms are severe then seek medical care. Best of luck.