RME or not

[recessedretard]

Im 15 years old and im debating whether or not to ask my dentist for an RME i can only fit my thumb in the roof of my mouth and if i get it how much deformity should i expect?

 

[recessedretard]

And if i have non sliding braces on my upper teeth will that cause my maxilla to not achieve forward growth with puberty?