DPO help!!

Ok so long story short...

I’m basically trying to figure out how many dpo i actually am?

My period calendar app says I ovulated the 28th

glow app says I ovulated the 31st

My periods are 7 days long and my last period was July 16th - July 22

Previous period before that was June 20th - June 26th

So based on this assuming my cycles are 26 days long on what day did I “ovulate”?

I know its not 100% but still will give me a much better idea of how many DPO I am. Maybe ill stop wanting to test so early thinking I’m later lol.

Im thinking the 28 would be when I ovulated putting me at about 9dpo but idk...

Thanks in advance!