Actually, I don't think the OP acquired nature form. His map does not show the bit where mother nature hides. He appears the have missed the entrance to her cave.
Unless you have an old version of Aquaria, there should be a glowing pulsing marker on the map that shows a suggested location. It first points to the song cave, then the energy temple, then Mithallas cathedral. (though it's not a bad idea to go for fish and nature form before beast form)
That said, exploring is a big part of the game, I know that the lack of direction can be a little bit annoying to some people, but that was actually done on purpose.