Extremely healthy diet....don't have a bowel movement unless I drink a LOT of decaf coffee and wait....!?

I am a 17 year old female who has a healthier diet than most (high amounts of fiber from fruits and vegetables, no refined sugars or sweets of any kind) but my body doesn't have a bowel movement unless I induce one with a lot of decaf coffee....i'm very frustrated because I hate feeling constipated/bloated....I wish i could poop without the coffee but I go days and days without a bowel movement if I don't have the coffee :( what can i do (what else can i eat or drink) to induce more bowel movements without the coffee??