My height is 5'3 ft and my weight is 43 kg, is it normal ? and i'm a vegetarian how can i gain more weight?

Malnutrition: Your bmi is lower than normal. Some people are like that, but you should see your md and consult a nutritionist to help out. It is difficult to get all the necessary nutrients and essential Amino Acids from vegetables alone or at least use of other plant food may be necessary to give you all that you need. Gaining weight should be secondary at this time. This should answer your other question also.