More effort has gone into making hip belts bearable than any other aspect of the pack since the advent of the things in 1970-71. They were a relief to folks like me who regularly packed 70 pounds for professional reasons. They hurt, but we thought they helped somehow. What a scam!

Then we discovered that the real problem was improperly located shoulder straps. Today, you will see 95 pound young women working for the AMC hauling cases of canned goods (and beer) up from the gaps in the White Mountains to the huts using old wooden Trapper Nelson frames or (slightly) more modern aluminum frames - without hip belts. Why? because hip belts hurt unless everything is just right; they restrict movement; they put pressure on major muscle groups causing undue fatigue.

Several folks said, lower the weight. That's the best idea.

Otherwise, substitute a waste band for the hip belt and try lowering the attachment points of your shoulder straps and maybe move the top attachment points closer together. Shoulder strap adjustments for use with a hip belt are just different from those for the straps used alone. You might have to adjust some other things such as the back bands.

The waste band is to keep the typically high center of gravity of a pack frame from causing the pack to tip.

Personally, I don't even notice my pack when the weight is under 30# - without a hip belt. I can carry a lot more and have done so, but I can't imagine why I would want to without some really good reason.