Pregnancy Symptoms...Am I?

Ok, I started on Yasmin birth control May 10th. Had unprotected about a week later. My period was 3 days late and I had a light amount of bleeding...most of which seemed a brownish color. I have absolutely exhausted, peeing like crazy, feeling nauseous throughout the day, getting headaches and backaches like mad, I've got a runny nose for no particular reason and just the last couple days I have started getting these dizzy spells and feeling like I'm going to p out. I am not doing anything different from my normal daily activities. Could this all be just from the pill or could I possibly be pregnant?