6 weeks, slow rising HCG, brown discharge, no heartbeat

I have been very stressed out over my slow rising betas. This was my first IUI and my first time being pregnant.

10/11: 15

10/14: 43

10/15: 73

10/17: 166

10/22: 466

10/24: 647

Was super nervous about an ectopic but I had an ultrasound yesterday confirming the pregnancy is in my uterus. I’m supposed to be 6 weeks based on LMP but the sono measured 1/2-1 week behind and no heartbeat. I go back in 2 weeks to see if the baby grew and if there is a heartbeat.

I’ve had some scant brown discharge and mild cramping/twinges.

Anyone have anything similar as far as the slow rising betas etc and it end with a healthy pregnancy? #worried