[Closed] Backpacks that dont cripple your lower back

ive tried quite a few, including the latest low rider cambelbak skyline, which was supposedly made to alievate my exact problem (I think)...however it does, it is comfy per se, but I still get lower back pain, to prove its the backpacks, I wear a hip bum bag (fanny pack as our transatlantic cousins say) and I get no pain at all) with a water bottle on the frame, for night rides and winter rides when I don't drink as much

however soon as I put my big back pack on I get pain, circa 2ltr water and ONLY the tools I carry in my bum bag

so are there any bags out there less prone? or is a weak back causing it?

ive ended up just taking ibuprofen before a big ride on the weekend just to alleviate it for a few hours