Flat spot

My baby has a flat spot on the back of his head.. its maybe like 3 fingers big (like knuckle to tip). Its seriously bothering me like to the point where I'm obsessing... I've googled, and googled. Our 2 month appt is tomorrow so I'll be talking to the doctor.. I just cant stop thinking about it. I know that a helmet isnt the worse thing in the world I just feel like if that happens it's all my fault. Even though I hold him and rotate him

I'm so stressed about it.