I am stressed with school work. = This is possible, but not so common.
I am stressed from school work. = (School work makes me stressed). It is okay, but
"I am stressed out from school work" is more common.
I am stressed about school work. = (I am worried about school work.) It is okay and natural, but
"I am stressed out about school work" seems more common.
But, to me,
>>>> "I am stressed out BY school work." is the most natural, if you mean "School work is the source of my stress."
Note: in this context, "stressed out" is, in general, more common and more natural than "stressed" by itself.