Have you test packed it with exactly what you plan to carry on Camino, then walked around your home or neighborhood? You can leave the tags attached while you test the usefulness of the rucksack for YOUR needs.
Any decision regarding keeping the pack or not should be made only after trying it on for size and load carrying capability and comfort while doing so. If in doubt, add a bag of flour, kitty litter, large bottles of water, etc, to add 'dummy weight."
The 30 L volume is right in the 'sweet spot' for volume. Many of us find, after experimentation, that the optimal volume for a Camino rucksack is 30 - 40 liters. The size of each person, and their clothing affects this requirement.
Overpacking, or taking too many 'just in case' items also drives the volume requirement up. If you follow the advice here in the Forum, and pare down your load-out list to the minimum required, the 30 Liter pack should be fine.
Anything you find out later you need, you can by along the way. Recall the old saw that saw, "...bring half as much stuff and twice the money..." Well that holds true on Camino too.
I recommend you pack the rucksack as though you were leaving tomorrow. Then walk around with the rucksack on. Use your bathroom scale to weigh you with and without the rucksack to calculate the net change in weight.
Adjust the straps and waist band as appropriate. There are videos on the Osprey website (
http://www.osprey.com) to help you do this. If in doubt, go to
You Tube and search for "how to fit (adjust) a backpack."
Only after you do this can you make an informed decision if this rucksack works for YOU. But, on paper, you appear to be spot on.
Hope this helps.