Period n ovulation?

1)Well im 31day cycle n period used to be fr 6 days nw its only 3 and wanted to know when will i ovulate?

2) when im on period it hurts so much to sit on my bum why is that happening been ttc 2years finished my clomid trying for my 2nd baby😥 im losing the hope as i keep getting period .

Really want to be pregnant