5k xc time not improving, despite the high mileage

Did you do any sort of physical activity the summer before you ran the 17:39? Another sport?

You mentioned not doing workouts this year, which may play a role. Also, how do you feel your form is with the added mileage?

Some top colleges won’t even let their athletes run with a iron level under 20. A lot of times if you run very high mileage you can get burned out as well or be even more iron deficient. It’s also only your second meet of the year, I’m sure you will get down to 17 flat. Make sure you are doing tempo and intervals as well. High mileage alone won’t get you to the top.