Off the pill!

So I've been off the pill since the end of November. Then in December my body took its time to readjust to being off the pill. Light brown discharge for a couple weeks then my actual period came. My OB said the brown discharge was just the effect of going off the pill so I'm not too worried about that. But anyways, my boyfriend and I have been having unprotected sex and he finished in me yesterday. Glow says I'm ovulating. I guess my question is, how accurate can this be? And if so, how high are the chances that he got me pregnant?