Hi,
@Annie G -
I cannot disagree with the good advice provided by
@Arn and
@Kanga. However, they have a ton of experience and just might have forgotten more about pack adjustment than some of us will ever learn!
Try this:
1) Empty the pack.
2) Put the pack on and adjust the hip belt to ride just at or slightly over the hips. Adjust the hip belt for a snug fit but leave the shoulder and compression straps slightly loose.
3) Take the pack off and re-fill it as you expect to carry it but (and differing with
@Arn) put the heaviest items centered and closest to your spine! That is the way the packs were designed. see this link:
http://www.ospreypacks.com/en/web/how_to_pack_your_pack
4) Put the pack back on, fasten the hip belt,
then adjust the shoulder straps. There is no need to over-tighten. When, as
@Arn noted, you have them comfortably snug but can yet easily slide a finger under them, go ahead and fasten the chest strap.
5) Now go look at yourself in a mirror and see if the pack's top is level across your shoulders. Assuming your shoulders are normally the same height from the ground, you should work with the straps to get that line level.
6) After that, then you can use the compression straps to tighten the pack contents. This makes the load more compact and easier on the back.
(I see that
@nomadpeah just weighed in with similar advice.)
Do not under-estimate the impact of being even an inch off-level. The leverage can create significant forces which will result in pain, usually in the upper back.
If this does not solve the problem then forwarding your pack is probably the best bet. And, if you are having pain in your lower back, I would suggest forwarding your pack anyway.
Buen Camino!
B