So sorry to hear about your little kitten.
May he R.I.P.
It sounds like you did all that you could for him. It just wasn't to be.
Last October i lost my cat of 10 years. The vet said she had a virus and gave her an injection and the next day she died before i had time to tell her how much i loved her. I cried for a week and couldn't work.
So i really know what you are going through.
I think another kitten will really help you.
I also bought a silver locket and put a picture of her in it, so she's always with me.
As for having 5 cats, my friend ended up with 10 cats once and she never had any problems.
I have only 3 but would love another one!!