AF at 7dpo!

So this is my first cycle using opk and taking note of my body, but have charted my period days for 5 cycles, average of 31 days. Been on BC for years. I ovulated this cycle on CD16 confirmed with CB advanced opk and a strip, also had cramps that day. I am now CD24 (8dpo) and have had spotting since 6/7dpo. I have cramps and am sure AF is coming tomorrow. I'm sad as it's such a short luteal phase. Not really sure what to do, if anything?! Or just see what happens next cycle.