I believe that is squaring. Rather than a rounded tire, you have a tire where the center is more-or-less even with the edges.

I'm sure someone else will chime in on whether or not tire pressure is part of your problem. But while I imagine the tire can take more pressure then it's listed max, that doesn't mean it's advisable or even necessary to overinflate. As a heavier rider, you may be more comfortable at closer to the max, but even so, many people find a more comfortable ride below the stated max pressure. You should at least try that, and if you really feel that you need 90+ inflation to be comfortable, find a tire that is specced for that pressure.

Also don't expect that moving more weight up front is going to make the tires wear evenly. The bulk of your weight will always be rider weight, which will always be on the rear tire more then the front. Find a weight distribution that optimizes handling of the bike, not that optimizes tire wear. You may still find that you prefer 85% of your weight up front, but don't expect your rear tire to last longer as a result. It will still wear out faster then the front.

I don't know if that's a reasonable amount of mileage for those tires. It seems low to me, but then I run Marathon Plusses specifically so that I won't have to change them often.