Sleeping at an incline?

I know they say not to sleep flat on your back cause it can put pressure on uterus and decrease blood flow or something like that and to sleep on your left side is best but is it okay if i sleep on my back if I’m on an incline like this picture??

I have bad heartburn and reflux right now so I’m propped up using pillows but I can’t lay on my side comfortably so I’m on my back. Is it safe since I’m technically at an incline or still bad since it’s on my back still? Sorry FTM 33 weeks pregnant so I don’t know anything 😖😖😖