I need help

I usually, as in every month from the time I get my positive I have 12 days until my period. I ovulate 1 day after positive opk, have an 11 day luteal phase. I have the blood marker for pcos. I have regular periods and positive opks regularly. This month I started spotting at 9 dpo which I normally don’t spot. This am my temp dropped and my cervix feels low and open. I pretty much know my period will be here tomorrow. However is that normal? I thought luteal days were the only consistent thing in a cycle. Why did mine suddenly change.