1 year old not eating good

My 1 year old still cant really eat very good. I dont know if they are just really picky and dont like anything or if they just still dont know how to eat. They only have 2 teeth I dont know if that effects how they eat. Making an appointment with their doctor cause it's starting to worry me. They have frequent BM and pees. They have only gained 6 pounds since birth but had pyloric stenosis at 3 weeks which prevented them from gaining weight the first month or two of life.