What are the chances that i could be pregnant?

I had unprotected sex 9, 12 &21 of my cycle, i dont keep track of period like i should, i havent had sex in seven months, but ive sexually active in feb. My period is usually 5 or 6 in a half days long. But my systoms lately have been cramping, and peeing alot more than usual lately. My nipples got alil darker, they're usually light tan. What are the chances that i could be pregnant? And when do I take a pregnancy test??