My fingers are way too small?

bnm

So it's time to start looking for engagement rings. Boyfriend told me to look up what I want so I can give him an idea on what I like and want! I know exactly what I like and don't like. Including, pretty sure I have the exact ring I want picked!! The thing is, every jewelry I checked out doesn't resize to the size I need- being a size 4. Most say the minimum size they can go is a 5 or 6..and that is way too huge.

I have a promise ring right now and it was resized to 4.5 and it's still obnoxiously big. A 4 would be perfect.

How can I go about sizing even lower??? Does anyone know where to go?