Is it possible you are already preggers? I ask because opks can pick up the same hormone that hpts detect and if you've had positives this long, I'd be whipping out an hpt if you haven't already. Also I've noticed in a couple of my previous cycles in which I became pregnant that my LH surges last for days. It is also possible that your body tried to O last week but didn't for whatever reason (stress from ttc can be a factor) and is now trying to O again. Either way, I'd take it as a good sign and get to BDing! Good luck!