Any idea why I'm still testing positive?

Due to medical reasons, five weeks and four days ago I had to have a medical abortion done at five weeks+ pregnant. The abortion was complete, the gestational sac passed and the subsequent ultrasound showed a clear uterus, and the follow up two weeks later also showed nothing abnormal.

Four weeks and two days after the procedure, I got my period and it lasted for about 5 days. Immediately after, at exactly five weeks after the abortion, I took an at home pregnancy test. Imagine how freaked out I was when it came back positive!

Concerned, I went to the hospital to get checked. Again, the ultrasound was clear even though the blood test came back positive for hcg (though I forgot the exact level)

I have been on a low dose bcp since the procedure was done, and my husband never finished inside me. Could I actually be pregnant again, or could the residual hcgs still be present at high enough levels to register positive on tests? Other than slight lightheadedness and fatigue, I have no other pregnancy symptoms.

My husband is away on a business trip until the end of the week, and I'm freaking out all by myself here. Any help or support would be much, much appreciated.