Welcome to the board. You found a big group of people who have gone through the same sort of things that you have. Some of us diagnosed celiac and others told they are gluten intolerant. It is great you are feeling so much better so no matter what label you fall under you are doing the right thing. There are those of us who developed symptoms as children. I was one. There are also folks who don't have symptoms until later in life.
I hope your GI did an endoscopy not a colonoscopy. The endo goes in from the top and is the scope they use to check for celiac since the damage is found in the small intestine. The colonoscopy requires a 'clean out' prep and they go in from the other end.
Do be sure to read the Newbie 101 thread at the top of the Coping section as it will have alot of valuable info for you.