This is something we all go through, so you're in good company.
When I bought my Lowpro I thought it was going to end my problems. Wrong.
I like the design, but the waist belt is too high for my body, at 6'3". It can adjust, but it can never get down to my actual waist. So I have to wear it around my stomach, which is total crap. I pretty much gave up on it and it's in my closet. The only reason I don't sell it is because it would be a good padded bag for carry on for airline travel. And if you have ever packed more than a few miles with 40lbs on your back--you really do need a waist belt.
Solution: By a really good backpackers solid frame backpack, and stuff your camera bag into that but first stuff it into small day packs--book backpacks. I use padded day packs, like those with padding for laptops. Nothing fancy. Now you have a very nice weight balanced pack made for packing. The weight is actually over and carried by your hips, not your shoulders and back.
When I'm shooting from my car or on very short hikes, like down to the beach or along a 1-2 mile trail, I'll put everything in my Pelican case, and then load what I need into a small padded shoulder only day pack, and just carry my tripod. You can't beat the water and dust proof O-ring sealed Pelicans for protection and storage area.
When I'm away from my truck, I lock the shell with the pelican case inside, and I use a cable lock strung through both latches on the Pelican case and through a cleet in the bottom of the bed of the truck. If someone breaks the glass to get to the inside of the truck, they then have to also have cable cutters to remove the Pelican case.
For walking around, I use a Domke Vest, not for lenses, but for other light material I use, like lens covers, a small plastic 2x2 foot tarp I use to change lenses, and other things like batteries and filters. If I need more lenses, I just stuff them into a small backpack and wear that too.