@Diff16
You don't want a pity party???
Well you deserve one. You poor thing 
It's only been 5 weeks since your brother died, and you have other issues on top too, like an ill mother and a family of your own.
You need to take care of yourself. Don't work too hard. Can you have any time off? Maybe ask the doc to write you a note for a few weeks off.
You are only 'not crying' coz it's not hit you yet.
My pal's mother died a year and 3 months ago, and it's still not sunk in properly. She still hasn't cried. Not even at the funeral. And they were close.
She said she forgets she is dead sometimes, and speaks about her to people in the present tense. She dreams that she is visiting her, and when she wakes up, it hits her that she didn't visit her (and she is in fact, not here anymore.)
Grief is different for everyone. One lad I knew some years ago, (he was 21,) went partying and clubbing the day after his mother died and got pissed, and then went for the weekend to Blackpool a few days before her funeral.
People slagged him off and said his behaviour was awful, but people deal with stuff differently, and he was dealing with it in his own way - by shutting it out.