I’ll be interested to understand how you move forwards and for you to share on here as you do (even if that means you continue to monitor it). In some ways an upper chest AVM seems to me to get close to the neck AVM that @Stephanie20 has and it may be that you have a friend in her. Her story can be found here: Has anyone had an AVM in the neck?
Unfortunately, you’re among the rarest folk that we find here, so I can’t find very many friends for you.
Richard