Check out the Cargo Endurance range ..
Soft (load them up and then 'compress' them with zips if required
) strong, well made, expanding throw over bags. A better, more practical shape and design than the Oxford fancy bags, Lifetime Guarantee, etc etc
If you can't get everything you need for a two up x two weeks trip into these and maybe a small tank bag for the bits and bobs .. you are lugging way too much junk!
All just in my opinion of course.
Stay Safe
Polar Bear. Spain.