Positive blood test a month after medical abortion

I had an abortion using the pills a month ago. Went in for an unrelated procedure today and they did a blood test which came back with a positive pregnancy result. Does anyone know if this is more conclusive than a pee test? We had unprotected sex the day before my two week follow up which showed the pregnancy was terminated with one little blood clot left to pass. I started bc immediately but We've had unprotected sex a few times since then as well. Stupid decision I know and it has me freaking out. Do I just need to wait and do another blood test in a few weeks? Help!