Your watch is using 133 calories per mile. You have adjusted it to 80 calories per mile. Mine is using 110 calories per mile. This includes large stretches of 3.5 to sometimes 4 mph for the first two miles. You are in better health than I am. So your calories per mile should be lower than mine for the same speed. However, I do think what you have adjusted it to is very very conservative. Furthermore, if you have been working hard going up and down hills, then you have burned even more calories. I can see where your watch is too high. But there must be a better way. Maybe you should use that calculator that computes calories burned during a walk. I think this figure would be more accurate for you.

Here, I will do this for you. I put in your age, which I made up as 45. I put in your height as 5 foot 10 inches. I think that I remember something like this. I entered 160 for your weight. I used a met value lower than the norm 3.5 for walking 3 mph since I think you are in better shape compared to the average person. I chose the much lower value for this activity of 3.0. This should make the calculated value conservative despite what may be erroneous data that I entered. The calculator comes up with 415 calories, which is a value between your estimation and your fitness band. I suspect the actual value is even more. Your value that you chose as 320 calories is 30% lower than this.

Food for thought. FWIW