In reply to Diana Smart:
Here's a left field suggestion:
I'm also a 5'4 female and recently replaced an ancient Osprey Mutant with a Mystery Ranch Sceptre. https://www.mysteryranch.com/scepter-35-pack
It's an American company, well known for making military packs, which means they understand how to set up a pack to take a lot of weight without you hating your life too much. One issue I had with the Mutant was that its weight distribution system was a bit rubbish. If I had a long hill day or was carrying full winter kit, my shoulders would be killing me. I lived it with this for many years, but when the bottom of the Mutant became more Gore-tex patch and Tenacious tape than backpack, I decided to look for a new one, and priortitized finding one with a comfortable carry system.
A lot of mountaineering packs are aimed at the fast-and-light brigade. Stripped down shoulder straps and waist belts. Screw that.
When you're only 8.5st, full winter gear or a climbing rope and rack ends up being a not insignificant proportion of your own weight.
Anyway, the Mystery Ranch pack feels amazing. I took it out in full winter mode on a 16k day this past weekend (okay, there was no snow, but I was prepared!) and it did not feel like I was carrying that much weight.
You can get them in the UK pretty easily. I got a deal on mine through the Absolute Snow website.