How do I make the flap/tap t sound as in words like: better, matter, stutter, moto, but I'm, bottom and so?
Being neither a speech therapist nor a physician, allow me to make a simple suggestion without the use of jargon (technical terms) for speaking American English:
- Start to pronounce each of your sample words as if you intended to make the hard D or T sound
- When your tongue is on the roof of your mouth, rather than forcing the tongue down (with your breath), relax the tongue so that a gap is formed
- Continue with the next syllable (-er, -o)
Please let me know how this works for you! Although using the softer D/T will sound more native, you will likely find it beneficial to be able to replace the soft D/T with the harder D/T for better clarity when singing or speaking to a large group.