Post miscarriage HCG question

I miscarried on August 1st 2017 at 8 weeks and 2 days. So I bought cheap test off amazon to see when I'm negative. The doctors have been Drawing blood every week since. HCG went from 7,500 to 139 the following week and 26 this past Tuesday. I just took a pregnancy test and its positive. The test reads 25. Shouldn't it be negative? I am having my blood checked again Tuesday but just curious. I know it takes a while for it to go back to zero but i just figured it would be negative. Top is from this morning bottom is from last night. This whole process is frustrating :(