OPK says I've been ovulating for a week! Confused

Gabi
So we've been casually trying to conceive for about 6 months (I came off BC but wasn't tracking anything)
My doc told me to start tracking my ovulation using an OPK, but I'm confused with the results.. My last AF was 2/18 and lasted 4 days. I got my first positive strip on 3/6, and every one since then has been positive - the test line is significantly darker than the control. Hubby and I BD 3/6, 3/8, and 3/10.
I've heard that sometimes OPK's can detect early pregnancy.. Could I be pregnant? Or is there something else that could cause the positive OPK for so long?