Baby getting a flat head

Marcy

I am a FTM and have a 3 week old son. Im so worried about him getting a flat head from laying that it’s unreal. He sleeps on the back of his head at night and during the day most of the day I hold him while he’s sleeping and lay him on my chest making sure I turn the side of his head that he’s laying on every so often. I’ve realized this isn’t reasonable and I’m going to end up making him want to be held all the time because I’m holding it for probably 90% of the day. Is it easy for infants to get a flat head or does getting a flat head tend to happen from babies laying in a device for the majority of the day as well as at night when they’re sleeping?