I had the six month smie treatment recently and my braces were off last Friday! It was absolutely fantastic

My front teeth were out of alignment and had to be rotated and my canine pulled in as I had an overjet on one side.
I have a fixed retainer which i absolutely adore but today I received the dreaded removable. Put it in and it is ridiculously uncomfortable. When I talk I lisp, I can't stop salivating and sometimes it pops off which is quite painful on my tender teeth! i checked with the ortho and it does fit correctly so apparantly this is just what a removable is like

She told me to pop it in for a few hours when I first got it and then wear it nightly until I next see her on March 15th. But I already know I will seriously struggle to sleep with this thing in my mouth! I know you should always follow the advice of your ortho and I WILL wear the retainer but I was wondering whether:
a) teeth can relapse significantly if you have a bonded retainer but do not wear your removable?
b) how good bonded retainers are in the long run?
c) will I have to wear removable for the rest of my life?? I opted for bonded because she initially informed me I would only need bonded and I now feel a bit disheartened because I despise these removables! Braces were a breeze compared to how bulky these were


Thanks for your help guys

Shortie x
P.S. I would like to reiterate that I AM FOLLOWING my ortho's instructions as I know it's silly not to, just unhappy about it!