Pregnant or levels still elevated from previous pregnancy?

I started miscarrying on April 12th at 6weeks. That Tuesday, the 17th, it was confirmed I already passed the sac but had lingering tissue that I should pass on my own. I was prescribed Misoprostol and bled off and on for 2 1/2, 3 weeks. I had sex last Saturday, the 28th. I took a test today because I haven’t been checking to see if I would get a negative since the miscarriage and thought for sure that by now I would have one. I got a quick positive. Could I be pregnant? Or do you think it is still picking up levels from my previous pregnancy? Any opinions would be appreciated.

EDIT: Thought maybe I should add that tonight I had brown spotting. Which is the first time in several days.