My tongue is wayy too big for my palate and makes my speech feel awkward and non-succinct, really annoying. I can't roll my Rs great either but I could do it after some practice, like I cant transition into a rolled R mid-word as in the word Glorious, but I can sorta flick my tongue down to make a single trill which works well enough for me. It took a while to learn how to Rrrrrrrrrrrrrrrrrrrrrr trill but lots of hip hop made that pre easy and now I can do it on command with full confidence lmao. Ironically I read somewhere that pronouncing a normal R is a challenge for most speakers learning English so I guess the dollar has two sides.

Practice practice but have faith that with improved posture and palate form you'll slowly gain the abilities of the full human sound :)

peace and love brother

@maxillest

Thanks a lot bro. Really looking foward into learning it before Semptember. Anything else that helped you in particular? Anyways many thanks to you. Your comment really inspires me 

@goofysniper

As far as I know It's a case of blowing air out your mouth and then putting just enough pressure on your palate, either mid palate or forward all the way to your teeth works too. Then it's as simple as adding your vocal chords into the air flow which creates the sound. I dunno how to apply it in language very well though, a consistent rrrrr sound that you can carry on.

But for a single R like a "newbie" trill you make the r sound, then take the tip of ur tongue and slide it along the top of ur palate and down past your teeth to sorta flick down, makes a sorta "rha" sound. Anyway I'm no speech tudor but I hope that helps

im sure there are heaps of guides online and on youtube etc. that would do a heaps better job than me tryin to explain this if u got no idea what im goin on about but good luck 

Yes there is a correlation between CFD and speech problems. I used to sing a lot as a child and could sing and speak freely until I got braces in my late teens. Ever since then I've had vocal issues as the teeth do not come into contact properly and palate was reduced. My guess would be that the teeth contacting properly helps vocal cord closure and prevents unnatural jaw movement so you are not letting too much air escape when you speak or sing, and obviously the size of the palate is important for breathing and resonance. 

I think there is some correlation, but with practice and time it'll not be noticeable. Severe problems like crossbite/openbite might be different thought because of mechanical difficulties.