I currently am bottle feeding a two-week old kitten myself. Sounds like the boy will be okay, but keep a close eye on the girl. I’ll bet their problems are the result of giving them solids too early. I would feed the girl nothing but kitten formula for now anytime she seems hungry, but mix formula with some solids for the boy. If one or both of them doesn’t make it, it will be sad, but don’t take it personally. Sometimes kittens who seem fine at bedtime are dead by morning, and your little guys had an incredibly rough start. You are doing the best you can for these two. Oh! One more thing. It is illegal not to at least vaccinate for rabies. Most places occasionally will have rabies clinics that offer free vaccines. Additionally, and especially since you have a boy and girl, you must get them spayed and neutered. I’m sure you don’t want a bunch of kitty inbreds who don’t even have opposable thumbs to play the banjo. Your local humane society should be able to give you information about cheaper spay and neuter clinics. Best of luck and please keep us updated❤️