Could I be pregnant? ?

I'm only 17 turning 18 in April so I know my hot flashes aren't menopause. I keep going from being constipated to having diarrhea. I had a UTI but even after I got rid of it I still keep peeing lie a freight train. I've also been really emotional lately but it could have been the fact my paw paw was in the hospital (I'm not sure since I also had happy, horny, and pissed real easy) I haven't really had tender but the do seem fuller and once in a while I get slight pains that are sorta like muscle cramps. And like a week ago which would be a week after I had I had cramps like menstrual cramps but I shouldn't start until either the 14th or 18th of this month I don't remember which. Am I pregnant or is something else going on? I plan to take a test this Thursday since it will be 19 days after I had and possible the day after my period is due since I can't remember when I'm suppose to start. Plus 2-3 days before my period is due I get cramps and then they go away once I start. If I'm suppose to start tomorrow then I should be cramping and I'm not.