Sounds like you've done a great job so far. Keep it up. That's the ONLY thing that'll get rid of the gut. Some people hang on to it in different places. Abdomen, hips, thighs and glutes being the most common places. I don't know about your body frame, but I think your ideal weight may still be a bit below your current. That is why you still hang on to the gut. Sit ups will NOT get rid of the flab, only strengthen the muscles.
ChipR