Generally I'm not a fan of feminizations, but I actually like
Timothea. A great nickname would be
Thea, but since you're planning on using it as a middle name, I suppose that isn't relevant.
Faye is not one of my favourites, so I'm don't really like the combo. It's a nice way to honor both your father and your mother though. But personally I'd go with some other form of
Katherine to honor your mother.