TALKING TO FAST..HOW DO YOU SLOW DOWN? ):?

ok so ive been told by my family that i talk too fast.and when im on the phone my friends be like "what?"..they don't understand a word im saying.that gets me pretty mad.i don't think its because im nervous..i'eve been talking like this for a long time..but now its really getting on my nerves..i talk soft too ive been laughed at because i talk wwaayy soft..i try to get louder but i cant...this also suks because im a choir student at my school..im thinking of giving up cus of my voice.my choir teacher already told me about going to the ENT doctor but i havent cus of personal reasons..any wayss.any ideas on what to do with my voice??..... thankss.!