920 kWh is about what I used last month for a 2000 sq ft house in Tucson. Like you I watch my usage pretty closely, but when that AC kicks on I hear a cash register opening in my head. If you're in Tucson, TEP (Tucson Electric Power) has an app that lets you look at your power usage in monthly, daily, and hourly increments. When my AC is off, I'm normally using about 300-400 Whrs per hour (if I'm home, about a third of that if I'm not), but with the AC on its normally 2-4 kWhr per hour.
A big step to lower your electricity bill is to move to time-of-day and/or peak time billing. TEP essentially charges half price per kWhr if you can move your usage off of peak times. Right now peak times are 6am to 9am and 6pm to 9 pm. Since it's still pretty warm, I have my AC come on to cool down the house from 5 to 6 pm and then it shuts off from 6 to 9 (peak time) and I use ceiling fans, dress appropriately, cold drinks, or just good-ole "not being home" to stay cool. The risk with these billing plans is that if you're not paying attention and your demand spikes during a peak time, the resulting demand charge can actually be more expensive than a traditional billing plan. So you have to actually think about your electricity usage, amazing concept to people I've told this to...
I also bought a plug-in power meter to track down vampire loads around my house and moved a lot of electronics to switched outlets in the house so I can completely shut them off. This was cheaper than buying "smart" power strips. Last month I had a local company blow in 8 inches of additional insulation in the attic, installed a new energy star ceiling fan, and modified 2 other ceiling fans to use LED lights instead of the original halogen bulbs (halogen bulb in an energy star ceiling fan is stupid...).