Just an observation. I'm not quite 50 yet, only about 43 atm.
I had looked at the available companions and saw Blizz! Loved the idea of a Jawa companion! Looked forward to getting him.
I went from planet to planet, to planet to planet...until I finally got him. Picked him up right at the end of Act 2, and (at the time if I recall correctly) had about 11 levels to cap.
Why is it that we seem to pick up our last 2 companions so late in the game?
Granted I could have leveled faster/skipped thru quests if I played on my own. I play with my wife's Sith Warrior and she picked up all her companions by about 32 or so....