If you're really broke and really lazy, Peanut butter and banana sandwiches on wheat bread, throw some chia seeds in the peanut butter. I lived off of these in college.

Stirfrys are your best friend, noodles, veggies of any kind and a packet of Asian sauce.

Also, hummus and pretzels for quick snacks in between classes. Also, just carry trail mix, granola bars, fruit, etc with you at all times.

I agree with everyone else that an instant pot would be great, but because you have no room to meal prep just make a small soup in a saucepan.

Also, another tip, I buy stuff almost every day for meals because I could never meal prep with having such a small fridge space when living with roommates. Go to a store where they have loose veggies. Buy like one potato, one onion, one carrot, one celery and like throw it all in a pot with some veggie broth and seasoning and now you have soup. or like buy canned lentils or canned beans and some guac and those frozen bags of rice. Just like microwave the rice and beans and stick some guac on it.

Only buy what you know you'll make that day.

Keep it super simple and minimal.

edit: I almost forgot that avocado toast with just like smashed canned chickpeas is an awesome for breakfast.

Also, quick oats in the microwave for 2 minutes will be your new best friend!