It is not just the size of the wire that matters but the shape ( rectangular, circular) and the material from which it's made that matters( Nickel Titanium, Stainless Steel, etc.)
You cannot use the rectangular stainless steel wires until your teeth are pretty much all the way straight. So if your teeth are a little wonky than you are probably in a Niti 0.14 Wire. But, only your ortho will know for sure. I always just ask the assistant so I don't seem too nosey with my ortho
My stainless steel wire is 0.19 x 0.25 . I am pretty sure that all rectangular wires have the, by 0.25 on the end.
Don't quote me on any of this because this is just my basic understanding of the wires.
Hope I helped.
Oh and to add, when you ask your otho assistant if you're still in the 0.14 Niti wire and she does say yes than I would ask your Ortho how your treatment is coming along and if your teeth are on track.
Nothing major didnt happen yet. 
