I would stress the importance of getting a backpack that is the correct size in the torso length for your body. As stated in other posts, smaller packs that do not sit on your hips will put the stess on your shoulders.
When I was going through this same decision, I was looking at the JetPack. I am a 6 foot male with a long torso. though the JetPack held all my gear, the waist belt was too high and did not comfortable put the weight on my hips.
I opted for a bigger 45L pack that was longer and a better fit to my body. I only needed a 30L pack for my gear, but the pack size made all the difference. I was very happy with my choice.
I would stress picking an ultralight pack. Especially on the Camino, you are not in conditions that are severe for a pack. It is not getting dragged over rocks, poked by branches, etc. The ultralight packs by GoLite, REI, Gossamer, etc. would be my choice. Nothing over 3lbs. at all and preferably closer to 2. Given you are a woman, you want to keep your weight lower, because your total weight is less. At 180lbs I have an easier time carrying 15lbs than my 100lb. daughter would. She used a Gregory Gpack and was happy with it.
Find a pack with the ultralight materials and that fits your torso well. Take your Camino gear to the store, load the pack and carry it around for 30m to an hour. that is a good test.
Good luck.
Rambler