Even though you say the air is blowing good I would go ahead and clean the coils off. I use a pressure washer but if your not careful you can bend the fins. Apply lots of coil cleaner and wait 10 to 15 minutes for it to soak in. REALLY wait, don't get impatient!
Change your air filter every 2 months, every month if you have pets.

You definitely need more insulation in the attic. That and keeping the eves clear for air flow wil help you a lot.
If you really want your electric bill to go down you can install an attic fan with a thermostat to start and stop it.

I have the same problem with my insulation. It's clumped up and even missing in some places. I'm going to level it out and put up some more but not until it cools down a little.
At least my AC shuts off eventually!

Danny

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