I don’t have the app (well, for main facebook. Still have messenger as a friend group uses that as the primary communication medium) but do have a few friends who live elsewhere on there so keep it around. It’s also my yelling into the virtual void place but with feedback from folks I know.
I mean, just reading that question as one long run on sentence certainly didn’t make me think of you as an adult.
Also, might be a language thing, but buddy has almost no age connotations and is used pretty frequently across age groups.