HCG test 6 weeks

Hey ladies! My doctors office is closed already so I can’t talk to them until Monday but I got my lab results from todays hcg test. I’ve had them drawn 3 times this week and here are the numbers

Monday 9,400

Wednesday 16,000

Today (friday) 23,432

That seems low to me since they are not technically doubling but this is only my second pregnancy - the first ended in a miscarriage in January...

I had an ultrasound on Tuesday where they found the gestational sac and yolk sac and was measuring 5w4d.

Just looking for input from all you mommas out there! Trying not to stress!