Memoir queries can break your heart.
"My husband died. I had five kids to feed. I figured out how to do it. I made it. I want to help other people in this situation. Here's my memoir."
"My child died of cancer. I want to make sure other families learn from our ordeal. Here's my memoir."
"My child died by suicide. I thought I would die too. I didn't. I want to help other parents. This is my memoir of how I made it."
I try to answer these queries personally. The amount of pain quivering in that electronic font isn't an optical illusion. Or maybe it is the tears in my own eyes, I'm not sure.
But the answer to these queries is almost universally no.
And the why is cruel: memoir, even memoir trying to help other people in similar situations, must have a significance for readers who are not experiencing what the writer did. There must be something more to the memoir. Something that makes it universal.
Without that, it's almost impossible to pitch this for general trade publishing.
The question to ask is "what does this story have to offer people who are NOT in my situation."
If you're finding a cold shoulder while querying memoir, this might be the problem.
It will help to get some objective opinions. It's hard to do this at a writing conference. If you sit down across from me and tell me this is a memoir of your child's death, my first response is not to say "well, what's in it for me?" even though that's what I need to know. My first response is to ask your child's name, how old s/he was, and to tell me more about her.
Thus, you'll need to find a place where you have more time. Time for people to get past the first shock of tragedy. A good writing class on memoir will help you. An independent editor will be of use to you.
Telling a larger story through the lens of your own individual story is what you need.
And if you can't find a larger story, there's a lot to be said for making the book available on your own. Even if you comfort just a few people, that's a good thing coming from a very sad event.