That sounds good. The larger you are to begin with, the more inches you will lose and more quickly. It slows down as you get closer to goal. That sounds right to me and you might see some months with evem higher inches lost based on how hard the exercises was, how much strength training you are doing and...of course, nutrition, nutrition.
I am close to goal...roughly 20lbs away and in the last three weeks I lost about 3.09 inches overall. During a 3 month period doing a packaged DVD program..I lost 19 overall inches. So, yes...totally doable. You can and should only compare your measurements against your previous ones. I use a Myotape tape measure and take 35 measurements and pictures monthly. Keep track of it all and you will see amazing results. Nice to have a log to look back through.