Slow rising HCG?

Wanted to see if any of you ladies had slow rising hcg that ended in a health pregnancy…

My HCG level was 143 on Thursday

And 266 on the following Monday ( 4 days apart) I know they are not doubling like they should be which is why I’m worried.

I had an ultrasound but they were only able to tell me they see the start of a gestational sac but can’t confirm yet. The ultrasound was also the same Monday I had the 266 HCG.

Going back in for blood work tomorrow, Wednesday.

Praying for the best!