Metformin and earlier ovulation?

I was put on 500 mg metformin in June, mid way through cycle. Raising to 1000mg then up to 1500mg for this cycle.

I came on around when I should have last cycle, I have PCOS but my cycles are give or take 31 days although I get severe pain as my cysts pop after I ovulate (if I do) and it kills the egg.

This month I should, according to the tracker, have ovulated yesterday. I'm on CD19. However, I have no usual symptoms.

However last Saturday for the first time I had brown spotting, and for 2 days before EWCM. Cramps Saturday night into Sunday morning. I've never had brown spotting before, ever. I felt good so I feel I ovulated. Since then I've been bloated all week, and few spots on my face even though I'm on metformin!

I'm not tracking because I want to remove the pressure on my partner and I. Knowing I was supposed to ovulate yesterday meant we didn't have sex as he's pressurised - plus working and all that. I hate to put pressure on him.

I have a blood test tomorrow to see if I ovulated and check my hormones etc but does anyone know if metformin not only regulates your cycles but potentially shortens them?