Well, looking at what you've done, I'd say there's alot that you don't even NEED to get. You do need Nature form, but is Fish form necessary? It's well out of your way but I suppose if you use it for speed...But I use wall-boosting for speed most of the time and I think that's faster than the fishy. Also why do you bother with spirit form? ALSO, the first health egg is in the very first area where you learn the bind song. Under a rock if I recall. The whale is completely uncessesary unless you're going for a "best ending" run. You don't need nautilus at all either. Also I agree that the jelly costume is very important. Free health means less time needed backtracking for crystals and food. But remember, Jelly's usefullness is far diminished if you get fewer health eggs.
Now these are just suggestions, I don't think I could possibly do this game in that short a time. I'm just not a speedrun kinda guy. My friend could tho, he's active on Speed Demos Archive.