I eat 600-700 calories a day and feel fine?

My friends and family say I need to eat more and always try to feed me. I’m 19 and I weigh 101 lbs (5’3). I lost 8 pounds since ending college 4 weeks ago. That’s mostly because during school I would eat fast food and soda for two meals a day and therefore eat 1500-1800 calories. I felt so sick and bloated all the time. Ever since school ended I’ve been eating 600-700 calories and feeling perfectly fine.

This is what I ate today:

Breakfast:

1 Keto Biscuit (80 calories)

Iced coffee with heavy whipping cream (40 calories)

Snack:

Protein shake (100 calories)

Cabbage salad (20 calories)

Seltzer water w/ flavoring (5 cal)

Lunch:

Sweet Potato (100 calories)

Carrots (20 calories)

Dinner:

Three chicken meatballs (140 cal)

Cooked broccoli (30 cal)

Dessert:

Keto brownie (90 calories)

Other:

Calcium and turmeric chews (60 cal)

= 565 calories

And I feel totally fine. I’m kind of tired but even when I ate a lot I was tired all the time. I drink about 2L of water everyday.

Is this really bad? Should I force myself to eat more?