Ovulation times change?

Lovely • IG: Plentifully.day TTC #4. Sept 2014 tubal reversal. Feb 2016 HSG: blocked tubes. May 2016 IVF: failed. Aug 2016 BFP turned to 4th loss
Not per glow but if you use opks, bbt or check cm have you noticed your ovulation time frame changes every month? This is my second month checking ovulation with opks and last month I got a positive 6 days after af this month still nothing after af