iPhone messages not syncing with Apple Watch and MacBook

My issue seems complicated to me so hopefully I can word this in the best way possible to make it make sense, so I have three current Apple devices my iPhone 15, my Apple watch and my MacBook Air all of which are under the same Apple ID and usually sync just fine. However, I ran into a snaggle trying to get my boyfriend and I's messages to fully sync and I think the root issue may be awhile ago it started sending to his email that he has setup and I tried to just add that to his already established contact that way it can sync but it seems that didn't work because for awhile it also created a group chat of him and his number which I thought was also strange. Fast forward to now, most of my messages don't sync on my phone it for some reason shows messages from awhile ago when he had to send SMS due to poor signal and I can't see messages from even a few days ago, and I just want to have access to all messages because I like looking back on them lol.

[Re-Titled by Moderator]

Original Title: Messages not synced