Positive OPK - pregnancy?

Anna | Expecting 1st baby 23.01.2019

Hey! So according to my BBT chart I am 12 DPO and expecting AF today or in the next couple of days.

I just took an OPK out of curiosity and it’s positive. I’ve heard that this can happen when you’re actually pregnant. Any thoughts?! I was going to hold off testing until tomorrow but should I test today?

UPDATE!! ^^^^