Should I stop?

Julia • FTM. Blessed with baby boy ❤️
So I don't know if this is okay but I've been doing this because I had no idea if it's okay or not??? But the whole laying on your back? Is it or isn't not okay? Or is it just different for every woman?
Im 36weeks 4days and I've been laying on my back ever since I was pregnant. My midwife never said anything? Should I be considered??