Is it possible to be purely centrist? It's either that, or I'm just really undecided.
Quite simply, no it is not possible. You will always strive for one thing more than the other and because all things can have political ramifications people simply lie or are uneducated when claiming to be centrist and/or politically apathetic. Plus, as the other lad said there are different concepts of Centre. The Overton Window is also going left very fast and even if it wasn't, any shift in it to any direction instantly redefines a centrist.