Break the Matrix

Should I get a palette expansion???
I'm 16, just had my braces taken out after a year and half, but still have a very narrow palates, top and bottom, where they get narrower in the back.

Definitely a Palate Expansion is needed, but does that cause the Maxilla to go backwards as it widens your Palate, or will it make it bigger and does create more space for teeth?

Thanks