I keep my house 68 in the summer. Sometimes 70. Sometimes I just crank the damn thing down and let it run into the mid to low sixties. (It will do it at night and morning) Before I shower for work I crank it down from 68 to 58 and let it run while I get ready to go in. My humidity is always 48-52%. I am a HOT person too. Always have been. I can't stand it above 72 either. I have a premium system properly sized for my home. No mold problems. Don't worry about mold. My cooling bills have never been over $60 which is something I cannot believe, but it's true.
I don't remember the exact heat load design, but it was setup for something like 70*or72* on a 96 outdoor temp. Something like that.
The pros here will help you. ( I am not in the HVAC busniess) However even with my setup I am just not comfortable above 72 at all. Don't let anyone tell you what you SHOULD be comfy at--it's your house. Other people freeze to death as soon as they walk in my front door...its just me that's weird.
However listen to the the guys, and you may want to call another contractor and pay him to clean up this mess for you. I had to pay a pro to come tweak my system because it was installed by clowns.
For future references--let your air conditioning contractor know what temp you want to keep the house before he gives the quote. As you can tell here most of the guys here like most of the world are 74-78* people. Makes a big difference in sizing.