First offense DUI in state of Mississippi?

Hi, I'm 19 years old and recently just had my first DUI. I had taken a few xanax and tried driving home, well.. I didn't quite make it. I ended up passing out at the wheel and going into someone's front lawn. I wrecked my car and it's totaled, but nobody was hurt (except for me- minor abrasions, busted lip, black eye… nothing major) and they decided not to press charges. Well, I spent the night in jail and got bailed out early that morning with a ticket for DUI first offense and my court date is in January. They are, as of right now, under the impression that I have a prescription for xanax because I lied and so did my guardian, who assumed that was the name of the prescription I am on for sleep aid. They searched my vehicle, found nothing so they can't charge me for “possession” or “controlled substance” as far as I know without further proof. I am curious, however, as to how much I am looking at spending on this… I know that I will at least have the DUI charge, if not anything else, and that I will have to have special insurance for a few years after my charge, and also there are classes that I will have to take to get my license back and I've heard that they cost anywhere from 150-500. I've heard that a DUI first offense costs anywhere between 390-1,500 or more. I passed the breahalyzer, and I did piss poor on the field test cos I was LOADED, no doubt.. but then again, I had just been in a pretty bad wreck, so I'm sure that if I decided to get a lawyer, I'd have a good argument over that. They didn't take a blood test, but they did have me write down what medications I was prescribed and I wrote down xanax even though I wasn't prescribed it. I have thought about it, however and a few years ago I was on topomax which sounds like it so I was thinking that maybe I could try and say I got the two confused and that I had mixed that with the sleeping medicaiton I am currently on and that it knocked me out. Anyway, any information would help. Thanks.