I've read posts on here of young runners (teens/20's) being able to eat whatever they want and stay lean, and how that tends to go away as they age. However, I'm (only) 20, 6'2", and 150 lbs. I run anywhere from 50-80 (peak) mpw and find that I definitely stress too much about my food/caloric intake. I seem to always aim for some arbitrary number that I made up, finding joy if I end the day below that number. This leads to me eating a lot of food that only I measure/prepare since I know its caloric content.
I believe that because of this I have been prone to injury/stress fractures/overtraining recently. I do eat a lot (at least 2.5k calories a day, up to 3.5 even 4k at times) but I am very selective with what I eat to the point I eat the same meal twice a day every day at times, which is a big bowl of oatmeal with banana and PB and then a big tub of greek yogurt on the side with some mix-ins. Many days that is all I eat in terms of variety, so perhaps I am deficient in certain vitamins/minerals.
My question is am I worrying too much about diet, especially at my age? I would love to just be able to eat intuitively and go out with friends and eat junk food "while I can" I guess you could say. At what age do you believe that you needed to start paying a lot more attention to your diet? Is 20 too young to be thinking this way? I don't want to abandon all my knowledge of health/nutrition, so it is not as if I would start eating fast food every day, but I'd definitely want to be more flexible/lenient with my eating habits.