very good point T---ie how heavy is your load Jno?
give us an idea of what ballpark figure it is, and the details like do you have a handlebar bag that weighs a ton.
also, I've noticed a real difference in putting heavier items lower down in my panniers
despite all the variables involved here, the general rule of putting more weight in front to counter our bodies weight more on rear wheel, plus heavier stuff lower down in panniers, should help improve things.
and throughout all of this, the bike could be fine and you just havent gotten used to a fully loaded bike--not a criticism, this is normal---just impossible for us internet forum folks to give you an answer other than some tried and trued recommendations.