Is pregnancy possible?

I had unprotected sex exactly 23 days ago today (tuesday) I was just switching birthcontrols so I had two peroids in one month so I cant tell you if I was ovulating or not. I know though I hadnt been taking it so it wouldnt have effected my ability to get pregnant tho I had taken it for on month previously so I think that can mess with your ovulation. Anywaysi started getting strange symtoms about a week later, like mild cramping and backache. I guess it could have been pregnany for my mom is extreemly fertile and gets pregnant very easily so it probably got passed onto me. I decided to wait and see what happened. As the next two weeks passed the backache became very prominate, my breasts started changing (aerola turned darker they began to be very tender) then I started gaining just one or two pounds, being hormonol, and having an increased appetite. I was was pretty sure I was pregnant. I told my mom and she took me to the doctor just yesterday and they did a urine test and it was negative.

So I thought maybe I just thought myself into all the symtoms, but I waited for them to go away. And they didnt. Can anyone help? My peroid isnt due for another week and a half at least, would that be to early to tell? Is it possible I really am pregnant? Or could this be something else? Thank you for any advice :d