The gap between my boobs is about two fingers standing up and become about three fingers when lying down. All boobs move sideways to some degree whether implants or natural. I think it also depends on how much loose skin you had to start with. If there is loose skin at the start, then the implants will probably move more on lying down. Sometimes it can also be due to the pocket been made too large during the op. I’ve seen some pics where the implant pockets were made so big, the implants slid sideways so much that the cleavage area had a huge gap lying down.
Did you have this right after the op or did it develop with time. Obviously if one had really large implants, the risk of drift over time increases due to more weight and sagging.
Hope it all works out fine in the end hun. *big hug*