Low HCG levels, was anyone in the same boat?

Lizzie • Pregnant with baby #3 😙 Team Green 💚

So I got my first BFP 3 days after my missed period. I got a blood test to confirm the same day and the results came back with 51.3 HCG. Technically I was around 15DPO. I am getting a second test a Monday ( 1 week later). I'm praying they go up.

Anyone had low initial levels but shot up after?

So nervous