Hcg levels ?

Okay I went on for my first blood draw and they were only 27. The second one 2 days later they jumped all the way to 111. And I got them done again 2 days later and they were 312. Is it okay that they didn't jump as much as the first time ? Or should I be concerned ? I know they still did more than double in just curious. Had a miscarriage in march and really want this baby to be okay. The doctor doesn't think anything is wrong. They actually told me they won't need to take my blood anymore until my first ob appointment next Friday and I'll be scheduled for an ultrasound. What do you ladies think ?