Negative but Doc day I'm only 7-8 DPO

✨Amy✨ • Just crazy for my SO and raising my babies together as though they were his and trying to have 1 more!
Long story short... I got a negative today. 
Other news doc says I am only 7-8 DPO if my  positive opk was on the 30th... He says my apps are counting the day I got my positive as O but it would really be Sunday or Monday.