how do you get the bottom middle Vanilla one???
Well for me, I just did the freaky route (same route you did for the top middle section) but tell him you love him, later when you head outside, don't follow shadow milk then later pure vanillas takes shadow milk back to castle.
So later when pure vanilla takes you out of the library and asks if you will go with him to help, say yes, But There might be other ways, but it worked for me that way ^^