Why Does My Vacuum Trip My Circuit Breaker
Honestly, with these kinds of protective-device trips, the problem is often exactly what says on the tin.  

An AFCI breaker is designed to look for arc faults, principally in the building wiring.   You've swapped breakers around, the problem does not move with the vacuum, it does not move with the breakers, it has stayed with the bedroom.  Occam's Razor: it's in the bedroom wiring.   

Since wiring problems are almost always at wire ends or devices, I'd preemptively swap every receptacle with a nice contractor grade screw-and-clamp type.