Help Me Calculate my Due Date?

Hi friends! I’m completely at a loss for when my little one is due... I had my LMP 12/15/19, took a test 2/12/20 that was negative, and got my positive test 2/29/20. So odd! I was worried about not getting my period and had an ultrasound on 2/21 that showed nothing abnormal (and definitely no baby), but my blood test on 3/2 showed HCG levels of 7-8 weeks gestation! I’m completely baffled.

I’d get an ultrasound, but am waiting for my health insurance to kick in, so I can’t yet. The suspense is killing me and I‘ll be worried about the baby until I see them on an ultrasound... Does anyone have any clue when my due date might be?