Well, just as a place to start, I would figure that 3000 calories per day should fuel your endeavor. If you can put together a meal plan that provides about 100 calories per ounce of food this would be just under 2 pounds of food per day. I walked the JMT in 1954 when I was 16-17 and planned on about 2 lb per day of food. I lost about 5 lb in 17 days of hiking. Your appetite won't be too good for the first 4-5 days of the hike so you might want to factor in a 2/3 ration diet to save carrying extra food early in the walk.

With all that said, your food needs will be pretty individual and the only way to learn food planning is by trial and error. IME though, it is more comfortable to take a little more food than you need than not enough. Do take detailed notes on food amounts and preferences to help with planning future trip and realize that your tastes and requirements will change mightily over the next ten years.

Have a great time on the TRT.😀🌵
May I walk in beauty.