HCG not doubling

Mere

So I had a miscarriage last November. I am high risk. I got a positive test on May 6th super excited. Being that I am high risk I get my levels checked weekly. Even though they are rising, they aren't doubling like they should. I had blood drawn on May 19th and my levels were 2913.68 just had it done again today May 26th and my levels were 5183.27. Now my very first level check was May 6th and it 82.04. I'm trying to remain positive but I just don't know. Did anyone else ever experience something similar and have a healthy pregnancy