Which exising AT&T plan sounds appealing to you? How much are you willing to spend per month? Take a look at some of AT&T's prepaid monthly plans that include data if you have not do so already. Perhaps there's one that you'd like better than your existing plan.
Nope, you're not alone. I do text somewhat often, but not as much as I used to. I guess knowing that you can send/receive an unlimited number of messages is relaxing and "playing it safe" as opposed to tracking how many messages you have left.