I wear a retainer every night and once i could pitch a e above the stave now I have problems playing the second octave of G (g above the stave) which has really discouraged me. Does a retainer chage your embouchure?

some people can play high but when they get their teeth straigtened they can`t do it anymore and they have surgery to make them crooked again. but if you`re using a retainer just don`t play with it in

I never play with it in I only use it in the night.

I had braces for 3 years... i learned with braces, with my teeth changing shape the whole time and then i got good... shortly after i got them taken off... no more friction sores from the metal but i sucked... then i got way way way better than ever in the shortest time hitting my double d`s and e`s again and now a year after ive gone so far that my band teacher (who was the best teacher in my province several years in a row) was amazed... if i can play like that with braces and now a permanent retainer you can certainly manage with a nightly retainer, its all about your mindset, if you think "gosh this is difficult i think i might never get any better" (a thought which i often had)
you will fail crash and burn... it hurts to do.. trust me on that one, but if you think "its not a question of if i get better its a question of when i get better at this" you will soar despite anything that might try to hinder you... trumpet skills flying for ever and ever higher and higher its all in your mind....(god i sound like im mentally instable)

good luck with your retainer

maybe you are not practicing as you should do.the position of your teeth has changed so your lips touch the teeth in a different way in time this problem wil vanish but only with correct practice