Im 21 weeks pregnant. i am worried about not putting on enough weight because my appetite hasnt grown much since i fell pregnant. is this bad?

Depends.: It depends on several factors. First is your prepregnancy weight. If you were underweight at the time of conception, then weight gain is more important. Second is the pattern of your weight gain. Minimal weight gain in the first trimester is common. By the second trimester, weight gain should be steady, on average about 1/2 pound a week. Weight gain in the 3rd trimester is more variable.