I decided to do some bricks and mortar shopping to get an idea of what I like and don't like. I have a torso length of 14", apparently, because women's packs starting at 15" are not comfortable. That limits me somewhat in the major manufacturers - I checked out Osprey, Gregory, Kelty, REI house brand packs because those were the packs that I could try out in person. I checked out kids' adjustable packs as well. Going ultralight may be something I do later on, when I am more experienced. The finalists were Osprey Ariel 65 XS women's pack, adjusted to minimum 14" torso height, and Gregory Wander 70 youth pack, likewise adjusted to 14". I walked around in the store, did squats, leaned over, etc for 30 minutes for each pack with a 27 pound load, and they both felt fine. They are 3.5 pound packs. Gregory Ariel was on sale for $210.00, Gregory Wander was full price at $200.00, and the Ariel had more convenient access to main compartment and had water bladder access external to pack body (the bladder slot is between pack backframe and pack body, so you could refill the bladder without having to unpack and repack the main chamber of the pack). Ariel also had a more comprehensive compression strap system.
Now that I have a pack that allows me to carry 30# comfortably, I can start training with graduated weight and length hikes. If I ever go look at ultralight packs, I might go for ULA Circuit, which is made in a kids' adjustable version, really the only ultralight pack with 14" torso capability, or get custom made . But that's in the future, and may never happen.