Uhh, -- not firsthand experience but I believe I've read or heard from users that the v-shape is a sort of explainable transition phase as you progress in expansion.  Perhaps something to do with a lag-time between the transverse sutural growth, the forward saggital upswing, and the spacing of the teeth??

In theory, an expander with a saggital screw (y-expander for example) would be more attuned to the forward vectors/forward expansion of the canines and front teeth.
However, I wish to advise that there may be benefit to maintained patience with the active plate. Thinking of your jaw as a complex mechanism trying to establish equilibrium -- i feel your front teeth are still adapting to the new equilibrium you have been creating.  And that therefore if you switch 0ut the forces acting on it suddenly, before the form/function of the skull adapts to the current changes being made... then... well. well... mm. anyways, i fear there may be something such as switching expanders too soon.  Just my thoughts on the matter. 

I wish to advocate that because the active plate is transverse mechanism -- the V shape would be a necessary evil/first-step to progress, and should resolve itself into a U-shape through both continued active-plate expander wear and the oral posture. 

Mind taking a picture of your appliance so we can see what the shape of the arch looks like?