Home is 1755 square feet built in 2006, unit is 3 ton 13 seer heat pump - the old unit would practically freeze us out of the house before it finally died. Windows all have curtains and all stayed closed. Have also installed ceiling fans in 3 bedrooms and living and family rooms which are running in clockwise direction to pull air from floor vents up off the floor. This is a modular home with blown insulation in the attic, not sure about the wall insulation. Also do not have any tree's to shade the house during the day.

You pretty much answered your own question, "Also do not have any tree's to shade the house during the day". Too many BTU's of heat, radiant in particular, that cannot be addressed by the AC.