IVF with FET and HCG levels no longer doubling at 48 hours, but still rising

Hi everyone,

I was hoping someone could respond and let me know if they have ever seen this before. I did my FET with our only PCG normal embryo on Aug 22. My HCG doubles at first every 48 but with this last draw it was more like 74 hours or so. My doctor didn’t seem worried, they said just check again on Monday and ultrasound end of next week. I’m currently 5 weeks and 4 days but it’s making me a bit nervous. Here are my HCG results

8dp5dt- 66

13dp5dt- 850

19dp5dt- 3100

I was expecting the one yesterday to be higher. Does anyone have any experience with this? Thank you in advance.