I know you raised the cat well.. but i think this time you should intervene this situation, the kittens are more than 4 months old and should be weaned already, the mama cat looks skinny, she can not eat properly because too many big kittens force her to feed them.. 😢 you should remove them and let the mother cat eat first.. from her look in the eyes, it looks like she needs you to help her, i feel sorry for her 😢