Miscarriage diagnosis but hcg went up?

Last week, when I was about 7 weeks and 5 days, we had our second ultrasound. I have had two miscarriages in the past so they wanted to see me early. The first ultrasound showed only a gestational sac and yolk sac. They said to come back again in a week and we should expect to see a fetal pole. But there still wasn't one. They told me I would be having a miscarriage, but I declined the D&C and said I wanted to wait and see what would happen. They did blood work a few times and the last time my hcg went up! I'm so confused. Now they're saying maybe I won't have a miscarriage. Has anyone else ever had a similar situation?