According to your states, your BMI says you're underweight, so no wonder you are having a ravenous appetite and getting easily winded, your most likely malnourished from previously under-eating and your body wants FOOD! Under-eating is extremely common on vegetarian diets done mostly to lose weight.
Stop starving yourself to try to lose weight. You'll just gain it all back plus some in the end. Fasts can slow your metabolism making it easier for your body to gain weight.
You want to eat your way thin naturally, not starve yourself. Look up Freelee on youtube who's super lean and healthy from eating a low-fat/high-calorie diet.