If you're really 94 pounds and 5'3, you're pretty underweight, and that can affect your periods. If you're dieting intentionally, see a doctor to discuss your health before you continue. If you're not eating because of anxiety, I feel your pain, but eat nutrient and calorie dense foods if you can only eat small amounts. If your body isn't running well, you'll feel off, get anxiety about it, the anxiety will make you feel worse, and it just keeps going. If you need help dealing with anxiety there's no shame in seeing a counselor, psychologist or psychiatrist.