pregnancy/weight

okay so everytime i go anywhere and ppl know that i’m pregnant (18 weeks) they all say how i’m so small and need to start eating.. it’s making me so worried bc i feel fine and my baby is doing fine but idk if me not rly showing by now is harming him or if it’s normal.. i weigh 125, i’ve gotten your to 130.. but i rly fluctuate between 122-130. is this concerning or normal?