Positive OPK 18 days past ovulation and period is 2 days late

I know the OPK tests for LH and pregnancy tests test for HCG, but I'm two days late and snowed in. I figured it was worth a try since I have extra OPKs. Anyway, came back with a faint line....

Has this happened to anyone else? Test tomorrow with fmu? Celebrate a BFP?

What to do? What to do?