When do the levels zero out…

How long does it take for the HCG to leave your system? The date of my ectopic/surgery my levels were only in the 700s. And I’m still testing strong positives 2.5 weeks later… what is going on? And I’m having a period??? I wasn’t bleeding much besides spotting here and there for a couple days after my surgery. Completely stopped bleeding for almost 1.5weeks and now yesterday I start bleeding like a period. But my tests are still coming up positive. This has by far been the most confusing and emotionally jarring situation I’ve ever been in… am I or am I not pregnant. Is it possible to have one pregnancy implant in tube, but still have the other egg (if I double ovulated) implant in the uterus. Could that be what’s happening