Did I have a miscarriage?

I am 28 years old...first pregnancy. My LMP was 2/1. I found out I was pregnant on 2/27 with a home pregnancy test and had pregnancy symptoms...sore bbs, frequent urination. About a week later, I began spotting and then bled (like a period) for a day. I spotted for the next few days and now all bleeding has stopped. My Dr. had my HCG checked and it was 25 on 3/3 and 34 on 3/5. She said I had a threatened miscarriage and we would continue with the blood work on 3/10 and 3/12. I go in for an ultrasound on 3/11. I don't have any pregnancy symptoms but my obgyn said that is not always an indicator of anything. I feel confused as to why my HCG rose (although it didn't double) and I bled. Could I have already had a miscarriage even if my HCG is still increasing? My obgyn also said that maybe I'm not as far along as I think and there's a slight chance it could work. I'm trying not to be too hopeful...this is an awful rollercoaster! Any insight would be much appreciated. Thank