Cab somebody help me with this time line my test lines are getting darker and these tests are 10 days apart

I'm sooo confusedddd so my doctor says I miscarried a baby but here's the story I've had my regular periods so I don't understand how could I have been pregnant my last regular period was September 9th and I went to the doctor October 1st because I kept bleeding and she comes back in the room and says ur pregnant! And i was like really? So she did a pelvic exam October 1st that day and she says ur uterus is still pretty small and the baby is still pretty small I have really irregular periods btw sometimes I don't get my period. And supposedly I would've been 5 weeks and 7 days. And she wanted schedule an ultrasound to see if I passed everything I haven't passed anything but a bit of blood it wasn't that much looked like light bleeding changing colors no gigantic clots either in my period for September 9th and the last period before that was August 5th . Now she doesn't want to schedule the ultrasound bcuz she says I miscarried I'm just really lost and confused so I'm hoping someone can point me in the right direction or give me some advice break it down to me and the reason she says i miscarried is because she checked my levels twice but I didn't see anything pass! Btw why feel my uterus and say "the baby is pretty small" and appointment is friday will keep updated.