Now I'm confused

The doctor called me with my bloodwork results.

I had an EMC July 10th, passed everything the 13th, bleed until the 22nd, had sex the 23rd and then bleed again until the 29th.

I went to the doctors on the 7th to get bloodwork because hpt were still showing up positive.

My HCG is at 45. She said it is actually higher then when I went in at 4 weeks on July 3rd. She wants me to repeat my blood test on Tuesday and then potentially have an ultrasound on Friday to check my uterine lining.

I just don't understand what this all means. I never got a quantitative blood count before. How is my HCG still so high?