Ovulation apps saying different days!

Kelsey
So I know I'm probably crazy but I currently have 3 apps to track my cycle and ovulation. Glow, pink pad, and Flo and they are all telling me different days for peak ovulation! 
I had a chemical on March 15th (first pregnancy and we got pregnant our second month TTC) and my bleeding stopped yesterday. I know my cycle will be off but I've read that with an early chemical it can just be considered a delayed period.
I haven't purchased OPKs just because I feel like I'm already obsessed with trying to get pregnant again and I don't want it to take over my life. 
I put all the same info about my average cycles in the apps but they are still saying different things. Anyone have experience with an app being correct?