Are both sentences OK?
I was a little kid at the time.
If I say,
Because of my age, I don't remember those days much.
As of my age, I don't remember those days much.
"Much" is not the right word. Instead, say "well".
"Much" refers to quantity, whereas "well" refers to quality. It is the quality, not the quantity of your memory that is the issue.
Say "at my age" instead of "as of my age".