Hi Maryindigo,
Although I'm a little taller than you, I seem to have a proportionally short back. Before I went to get a backpack, I had spent a great deal of time and effort researching the best and lightest packs. In fact, I went along to the shop to buy a specific Osprey bag.
Luckily, I tried it on, only to find that it was completely wrong for me. The guy in Snow + Rock was incredibly helpful in assisting me find the bag that worked best for me. The odd thing was that some of the women's bags really didn't work for me at all! Apart from ensuring that all of the numerous straps were adjusted to suit my particular frame, he loaded all of the bags that I was interested in with kit to let me feel how they would work in real life. In the end, I chose a Deuter Futura and I can honestly say that it did not cause me any trouble or discomfort on the entire 800kms that I walked.
I would very strongly suggest that you go to one of the good outdoor shops and get their expert advice. Most of the assistants are hikers, runners or other outdoor enthusiasts so it's not just sales talk. In my experience, they really do want their customers to be happy (so they keep coming back). Just tell them that you're doing the Camino, and there'll be someone who can help you.
(For what it's worth, you can always identify the boots, poles, pack you want and then check online to see if you come up with a better price elsewhere. However, I think that in the case of the pack in particular, getting professional help with adjusting it is invaluable.)
If I recall correctly, they suggested that I take the pack home and try it out with my own Camino gear to make sure it fitted and felt comfortable. Certainly all three of these retailers encourage you to take boots home to wear around the house for a week-10-days to make sure they feel OK. If there's any problem, they'll take them back.
If you can make it up to Dublin for a day, I can honestly recommend these, having purchased various bits of kit from them all over the years:
Great Outdoors, Chatham Street (off top of Grafton Street), D2
http://www.greatoutdoors.ie/
Snow + Rock, Dundrum Town Centre, D16
http://www.snowandrock.com/
http://www.snowandrock.com/store-dublin/content/fcp-content
53DegreesNorth - Carrickmines and Blanchardstown Shopping Centres, Dublin
- The Cornmarket Centre, Cork
http://www.53degreesnorth.ie/
http://www.53degreesnorth.ie/stores
The good news is that they all have sales running at the moment!
One final thought is that Great Outdoors sometimes run Camino information evenings, often in conjunction with a charity that is going to do a sponsored walk. I've never been to one but it might be useful for you. Keep an eye on their events page, or sign up for info to get emailed.
I hope that this helps and you find exactly what you need.
Buen Camino!
Maria