There is no reason why on 100 degree days you cant reach 74 degrees. Have you made concessions, sure. But texas sees more prolonged heat and you will continue to have problems unit you fix it.
I would get a building envelop person out to check out your house and see where the house is leaking from with a thermal imaging gun. AC units are typically designed for 90 to 95 "degree day" temp. When temps exceeds "design degree day" temp the unit runs longer and harder. Your ac unit may be low on freon or really dirty. Attic insul should be atleast R-38 and walls should have continuous insul of R-5 plus R-13 in the studs (IECC 2018 commercial). More continuous insul the better. If you have old windows and window blinds are left open this will bake the inside as well.
I have a 1935 house in Nebraska and have no issues with keep it cool on 100 degree days and 70% humidity. We are have a week of 115 heat index days right now. It cools better than my house. Its undersized for only 90 degree days but i can still keep it 73 and the house is in full sun due to no trees (newer development).