Lower than predicted HCG but progesterone good?

Would like to hear from women who know.

Based on my LMP I would be five weeks, 1 day. I went for bloodwork today and they called and said my hcg wasn’t where it should be for that estimated gestation but the progesterone was good. They want to retest my levels in two days.

How worried should I be? Is this most likely a case of late ovulation? I had a tiny bit of implantation bleeding the day of my missed period and didn’t get a positive test result until that day either so I thought maybe I had ovulated a little later...

Please help. I’m worried.

Update:

I took another test to ease my worried mind. This is mid afternoon after a ton of water. I feel better. By far my darkest lines.

Update #2:

To anyone else going through this: I had another test 2 days later and my levels were rising appropriately. I will test one more time again next week before my first ultrasound appointment.