How long does hgc stay in your system after giving birth?

I had my daughter 14 weeks ago and I have this horrible feeling I’m pregnant again.

We’ve been using condoms, but I know anything is possible.

I don’t want to take a pregnancy test and it be positive just due to leftover hormones.

My periods have been super irregular since having her so I have no idea when the next one is due.

I’ve been nauseous and crampy for about a week, but I also just stopped breastfeeding, so could the change in hormones from weening cause nausea?