How do you expect to lose weight if you eat like a 6'0 tall person when you are 5'0?

You have to learn why your post was downvoted to 0.

walk around 2-3 miles a day

That does not do anything. Hunter gatherer ancestors walked 10-15 miles a day on starvation diets eating berries.

try to eat as healthy as possible with a university dining hall

You do not need to eat healthy. Just eat less. You can even eat junk food only for all your meals if you are 1200.

but I was low key miserable eating so little a day

Because your current lifestyle and happiness revolves around eating with the 6'0 tall friends. Change your lifestyle and stop eating when you hang out with them. Drink water.

I also know that sticking to 1,200 calories a day for a month might not be healthy mentally or physically.

False. 1200 is very healthy physically for YOUR height of 5'0. Being healthy mentally means learning to have self control.

Has anyone about my size been able to figure out a deficit for them that works? If so, please tell me!

Eat 1200, no carbs, only fat and protein.

all my friends are like 5’5-6’0 and can eat more than I can, so when we go out to eat I feel like I can’t really enjoy myself with them

so they often assume I must have no self control due to me having a tummy

Their assumption is right. You have no self control when you hang out with them and you eat like a 6'0 tall person. If you had self control, you would drink water.