My training changes, as does my appetite. Although they are not always correlated (ex. During the peak of my season I am always super hungry on my day off - Monday - because it falls after 2 longer days of training) I typically know when I am going to be more hungry depending on my workout for the day. Because I know my body, I find it easy to plan my meals for the day. Taking into account my interning/life responsibilities, it only took a week or so to figure out what meals and snacks work best for my busy and active lifestyle.
Because I work so early in the morning on Mon and Tues (I start interning at 5:45am on Mon and 6am on Tues) I give myself 2 breakfast meals. Because my "lunch break" is around 9 or 9:30am, I start my day with a small serving of oatmeal w/ protein powder around 5am and then a heaping serving (with nuts, raisins and dry cereal) for my "real" breakfast. I don't see this as two separate meals but rather 1 filling meal spread out throughout the morning. This took a few days to figure out because I quickly realized that trying to work in the kitchen from 5:45am until 9:30 am, on a wasa cracker w/ PB (on my first day), was not going to cut if for my body. I was starving, my blood sugar was low and I was not enjoying the day. Thankfully, I brought along some nuts and fruit (and oatmeal) so I snacked whenever I could (which wasn't very often but I tried) and planned for a more filling breakfast for the next day.
I believe that counting calories is not an effective way of listening to our bodies in an effort to fuel for life and exercise. Yes, at the end of the day we want to consume a certain amount of calories to support our daily requirements but skipping meals and snacks, feeling starved all day or eating a large portion of calories in the evening isn't going to cut it when thinking about your weight, performance and health goals. Life is about balance, as is your exercise routine and your nutrition. It takes some experimentation and some good and not-so-good days but you have a long time to figure out what works best for you. Don't start tomorrow on your nutrition....start today.
Remember, as your life changes, so will your exercise and nutrition routine. I think you'd agree with me that even if life changes, we will still enjoy training/exercise and we will still enjoy putting good food in our body.