After her business my cat never smells pleasant and about her eyes?

My 6 month old kitten after she does her business she smells like poop. How do I get rid of that odor? and is it normal for a cat to poop a lot. I clean up her litter box and by night time it gets full!!! Today it got a little full so when she was trying to hide her poop in the litter it got on the towel and she covered it up with the towel. When I saw her poop on the towel I looked at her and she lowered her tail and creeped out of the room. The good thing is she knows it's suppose to stay in the litter box and not outside. She eat blue buffalo. Every morning she wakes up she always has brown stuff in the corner of her eyes. I always clean that up with warm water. She had inflammation in her left eye 2 weeks ago so the vet gave her terramycin for her eyes. Her nose always has like dried up booger. Is it normal for kitten to not be able to clean their own self up? I usually see older cats wiping their eyes, their nose etc themselves