Understand OPK help!!!

i got a positive opk a couple nights ago, all day yesterday they were positive as well and this morning it was barely negative but definitely not positive like yesterday. Glow changed my ovulation day to yesterday instead of today since i got a positive opk, before though on a different cycle i've gotten a positive opk in the morning and negative by afternoon and it changed my ovulation day to the day before. My question is, once you get a negative opk after a positive does that mean ovulation occurred? I also know testing OPKs after a positive is a no no no but i don't mind doing it and it helps me understand how long my surges are.