Strange... you should get it now because the "Blue world" needs 4 switches. (you have 3 stars in every world so you must have 4 stars in blue world)
SPOILER : Switch in Green World/Garden + My Progress Screen
As you can see in my progress screen i did all what you did but stars went into last place (Probably its a bug)
Also the "Green Switch" is out of the entire map on picnic table in that corner. (Red room has a tip how to get above the map: but im gonna tell you if you know where is dream catcher try jump like in this picture VVVVV)
I was using other method to do this but its kinda exploit . You need sprint too to reach it.
Anyway, when you do this and go out of the map you can see something nearby.