Low hcg but doubling...??

Tiffany

On Monday (3/7) I got a blood test done and my hcg came back at 24, then I got another one today(3/9) and it came back 55. It’s still low but it is doubling correctly... any comments or suggestions on what could be going on?

Past info: I have a 33 day cycle. My last period was on March 28th.

Any comments or if this has happened to you before advice would be greatly appreciated:)