Opinions pls

So I normally have a 30/31 day cycle meaning I would be due af on 21st. I had a near positive opk cd16 which is average and thought I'd maybe just missed the surge?. Anyway cd26 noticed changes to cm so did opk and line was much darker than test line so thought I must be really late ovulating this month. Glow now states my cycle this month is 40 days. My question is this- I've read that you can get a positive opk when you are pregnant? Should I test going off original 30 day cycle or wait? X