I think I posted the exact same thread a while back when I was looking for a backpack. I'm 6'6" and 270. I have a 24" torso and had a horrible time finding a pack that works. At 22", you'll be on the border, but you'll likely have more options.
GoLite and Mountain Laurel Design packs were all too short, but I liked them a lot.
Granite Gear and Gossamer Gear packs were close, but not close enough. I'm convinced Granite Gear doesn't measure the volume of their packs correctly though (they always seem small).
Osprey and Gregory fit great, but were entirely too heavy and don't fit in the lightweight theme.
The only pack I found that fit dead-on without paying for customization was both the ULA-Equipment Circuit and Conduit. I highly recommend both.
All of these packs are great in their own right and I recommend any of them based on your own preferences, weight needs, and fabric choices. As I said, at a true 22" you'll be right at the limit of all of them with likely greater success with ULA-Equipment, Gossamer Gear and Granite Gear. I found the Mountain Laurel Designs pack a bit too small.
Although I have never tried a pack from them, Six Moon Designs is worth considering. Perhaps others could chime in about them.
In a pinch, just ask manufacturers to send you a sample and they often will at the cost of postage. Others will even be able to modify it for you, again though, at a cost. Worst case, which is something I've done entirely too much, is to just buy it, try it on, and return it if it doesn't work and eat postage along the way.
If you want to go the custom route, consider a McHale. He'll do just about anything, but he is expensive.
If you only want to do this once and not worry about sizing, go with the ULA-Equipment Circuit or Conduit.
