No it's not way to small, it's a bedroom, not the livingroom. Much bigger than a 42" and it will be annoying.
I think those "distance" charts are formulated by the tv manufacturers so people buy the biggest tvs for the most money. 720p, 1080p either one in the 40" to 42" range will be good. I speak from experience and who in the world would put a 75" tv anywhere, what is up with that?