Are you living away at the college or do you commute just for the day?
I have been living away in dorms at college for three years now (even with a semester living in dorms at a university in Ireland) and I will be a senior in september, so I have lots of experience with PKU at college. I am on the Camino Pro system for formula, which is AMAZING at school (I'm not sure where you are, but I think it's only available in the US and Australia). The pina colada and fruit punch juice pouches are total convenience- I just grab two to drink in between classes during the day. The BetterMilk is a powder to be mixed with water, so in my dorm room I drink one of those with breakfast and one at night after dinner, and it's perfect for me to get my 60 grams spread throughout my day.
If you want to drink something that you need to mix all throughout the day, try experimenting with premeasuring the powder, putting it in a bottle, taking the bottle along and adding the water when you want to drink from a water fountain or something. I've done that in the past while traveling and it has worked pretty well.
As for food, the most awesome on the go snack that is low in protein for me is fruit, I just grab an apple or banana and I'm on my way. Other great things are snack size bags of Wise onion rings or little premeasured snack size baggies of things like popcorn and crackers. Also, the Nutricia low pro apple bars are a staple snack for me. Also a thermos or a cooler lunch box might be a good investment. My school has a big cafeteria with lots of options for me, and I am able to have a microwave and fridge in my room so I can do a fair amount of preparation myself. If you are dorming, it might be worth it to check with your residence office or your special needs coordinator to see if you could get special permission, that's what I did and it was completely worth it.
I'm sorry this is so long! There are lots of us on this website who are in/have been to college with PKU and we are glad to help! Feel free to message me if you have more questions!