cant gain weight!!!!!

ni

i been breastfeeding for 5 months now and i CANT gain weight, the nurse says i have to eat 200 more calories i think if i remember correctly but ive been doing that and still cant gain weight, i weighed 109 before i got pregnant and 144 by time i gave birth. i now weigh 107 and its actually driving me crazy, i dont want to be skinny skinny, i want a little meat on me 😑😪 please somebody help, give me weight gain advice