3 weeks post D&C

Evin • Momma of twin🌈 babies.
I underwent a D&C on May 31st; we were 11 weeks along.
Today is June 20th, almost 3 weeks later, and I'm still testing positive for pregnancy. I'm eager to get a better idea on where I am in my cycle and ovulation predictor tests keep coming back inconclusive (the test line is darker than the control line). At least I think that's what that means. 
The Dr said we were safe to try again right away. And, honestly, I want to know when my cycle restarted or what's happening in there. 
How long did it take for you to get a negative pregnancy test
Can you detect a LH surge on an OPK even with HCG in your system? Do OPKs work when you're still testing positive for pregnancy? 
Sorry for all of the question. I'm just really eager for some answers and past experience to help guide my expectations.