Sorry you are having such a rough time.
Fistulas are a complication that are not comparable to most of us who have a typical recovery with the minor setbacks that are more easily resolved. So, I don't think you will fall into the category of being able to predict a better outcome. For most of us, 6-12 months is the typical expectation for a reasonable function.
A lot of gas is usually due to too much bacteria. So you either have overgrowth or an infection/inflammation. Not surprising if you are dealing with fistulas. If you are already on antibiotics, you may need something different, including a combination.
Unfortunately, fistulas are notorious for being persistent. If it has not healed after a year, it is not likely to heal. There are a number of folks here with them that will probably chime in.
Jan 