chronic constipation

I've had an issue having a bowel movement 'naturally' now for several years. I am 24 years old, and otherwise healthy, I assume. It is to the point where I cannot remember the last time I went without the aid of a caffeinated stimulant of some kind.. usually coffee. For awhile, I was incredibly scared.. thinking that it could be a number of very serious ailments, including cancer. I still am. However, I went to a specialist a few months ago to face my fear head on, and he said that I most likely had a 'functional' issue, meaning it was not due to disease or trauma, but rather a mental problem, drug related (I take a very low dose of an antidepressant), my colon muscles have become weak, my mind doesn't transmit enough signals w/out the stimulant, etc..

I had a colonoscopy to confirm it was functional. The test results showed I had some a minor virus - but the doctor said that was just a very small part of the colon (like an inch) & that many people have that - and everything else looked normal. He said that would have nothing to do with what I'm going through.

He told me to increase my fiber intake, try to keep a schedule and get up in the day time (I work a graveyard shift), exercise more (I work behind a desk and get moderate exercise if any), as well as not to eat much after the sun goes down because the body cannot digest properly after that time.

I have to admit, I made a slight effort to follow this regimen, and then kind of gave up hope, because I saw no change. I also don't think that what he told me is correct. I don't think that my night shift or sleep schedule has any great impact on my colon, as I remember having this issue before when I worked during the day. Does anyone have any advice? I am really scared. It seems as though I now need more and more caffeine to have a bm. Sometimes I go 4-5 days without having one... drinking cups and cups of coffee. By that time, I have a foot of crap inside of me, and I feel horrible. I don't want all of this toxic waste lounging inside that long.. I know it's not healthy, and I want to be able to control my own body and not depend on anything to do it for me. I'm in my early 20's... what's going to happen 10 years from now? Please, someone, if you have dealt with this or have advice based on experience - personal or otherwise, I would GREATLY appreciate it.

Sorry for this long post..


Teri