Are you sure you are completely filling the tank each time. I level my bike an fill to the top of the inner ring. Just a half gallon difference could be another 20 miles.
All around town traffic will result in much lower mpg. I only get 35 or so around town, but have gotten as high as 45 with 100% highway miles going 70 or below. Most of the time I hit reserve at 115 to 125 depending on conditions.
One way to check is after you hit reserve and stop - how many gallons are you putting in the tank? If you were on reserve, you should be adding 3.5-4 gallons.
