My Toddler Is Not Gaining Enough Weight

Hello all, im just a bit worried. My toddler looks a bit skinny.. Gusto ko sana mataba siya. Kaya lang he is such a picky eater or rather, hirap lang siguro ako magprep ng meals niya since kabuwanan ko na. (Yes im preggy.) He has gotten much taller naman, its just that mas kyut sana siya kung katulad ng dati yung taba niya. Ano po ba pinapakain niyo sa 3 yr old kids niyo.. Meals and snacks. Juices or anything. Vitamins etc. Would really help if maicomment niyo. Thank you so much! From the mommy who is burnt out (lols), Ava