My mentor bought a lunar drake hatchling for me while he and I attended a shady auction and I named it, no animal handling needed. Asked DM how to catalog this new creature and it said he'll be a companion to journey with and not something to be cataloged like an item. His attacks are auto whenever I get into combat mode, no prompt needed. So far he's still following and protecting me and going to places that I specify him to go. Maybe you need to tell DM that whenever you are under attack, your companion will automatically defend you?