Are Tiredness, Headaches And Back Pain Symptoms Of Pregnancy?

I had unprotected sex my first day of ovulation cycle and the second day as well almost two weeks ago. The guy came in me both times. Ever since then I have felt more tired, gotten headaches easily, I feel sick at random times, I pee every hour almost, and my back hurts for no reason. Could I be pregnant? When should I test if I do? Could this be something else other than pregnancy?