Confused about glow

So, my <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> said that I was due to ovulate on the 12th, but my Dr said I should have ovulated on the 5th... I’m so confused now. Anyone have issues with the app calculating your fertile days wrong...

SN: I use ovulation kits and they were accurate and in line with glow..