How long will it take me to get pregnant after one shot?

Hi! I had my first and only depo shot on August 2, 2011. Which means I'm due for it today. I am not going to take it again. I have some weird symptoms and I'm not sure what they mean. Nausea Bloating Swelling/ sore breast Abnormal amounts of discharge Hair loss (scalp) Cravings Aversions to food and smells Heightened sense of smell Mood swings like crazy Cramping in my lower stomach Lower back pains Mild headaches I passed out once after getting up to the bathroom I don't have to pee every second but I don't feel like I have to pee until I'm about to burst I have taken 2 hpt, the first at night, which was a faint positive, the second in the morning, which was negative. I had my period on depo every month. I didn't think about tracking the days but it was every month. The first month it was spotting, the second it was a full out period with terrible cramps, and the third was spotting again. I was wondering if I could be pregnant, if I'm just coming off the shot, or if I'm about to start my period. Also, how long will it take me to get pregnant after one shot? Thank you everyone who will answer!:)