I'm a active college student too. Weighing about the same. I actually struggle with my weight a lot and don't want to gain any what so ever. I would suggest eating a heavy breakfast. Like cereal or eggs or toast and fruit. That will help add some calories into your diet. And since you're gone all day then bring some snacks with you. Such as granola bars, veggies, fruit or nuts. It sounds like you just need to add more calories into your diet. You can take some of mine. So yeah. Add more calories. Maybe you could do one of the things online or at your school health center where you count everything you eat and then find out if you need more of something or just calories in general. Hope everything works out for you! Have a great day. And keep running!