Um... I'm no expert on feeding, I've only had my snake a month or so. She's 16 months, 82 grams, feeding on 2 fuzzies a week but need to move up to hoppers.
I would think that an adult (older than your snake) would be eating an adult sized mouse once per week, or even every 10+ days depending...
My guess is that it sounds a little large. Any photos of your snake?