First of all, let me say that my first colonoscopy was pretty much a non-event – no big deal at all – despite the fact that I’m normally hypersensitive to having medical care inflicted on me. Much of it has to do with the right medication, and the right amount of it.
One thing that bugs me about stories like the OP’s is the apparently antiquated prep that is still being used. There’s no reason to have to drink 48 ounces or whatever of horrible crap as a purgative. The stuff that my doctor recommended was Pico-Salax.* It comes in a small box smaller than a cigarette pack and contains two sachets about the size of sugar packets. You dissolve one in a cup of water, and while it boils and froths rather evilly, its taste is not much different than lemon tea that happens to be not very good. After some period of time you have to take a second dose, which is kind of scary because at that point you feel pretty much purged of everything including part of your intestines, but that’s the procedure. Anyway, with Pico-Salax the only bad part of the prep was spending so much time on the toilet, but not the drink itself.
As for medication, my information may now be dated, but to my understanding there have been two procedures in common use, one supposedly allowing the patient to remain conscious but sedated, and the other a complete knock-out. The first is generally accomplished with a combination of fentanyl and midazolam. That’s what I had. I say “supposedly” allows the patient to remain conscious as I have no recollection of anything except waking up in a recovery room and not having any idea at all how long I’d been there. But judging from its effects right from the start, I must have received a pretty good dose. This is really important because I’ve heard stories from other folks having received the same medication and enduring a good deal of discomfort during the procedure.
The other medication option is usually propofol (Diprivan), which really does knock you out. I asked about that and was told that, by law, an anesthesiologist must be present and administer the propofol, and since none were present, they were going with the first option. Anyway, it didn’t matter, because I got enough of the good drugs that I was completely unaware of anything.
Best of luck. It really is a pretty minor procedure, and as many others have said over and over again, the worst part is the prep where you life seems confined to the toilet and you can only consume clear soups. And it’s important to have it done. There’s an alternative test that can be performed called the fecal immunochemical test (FIT), but it’s not nearly as informative as a colonoscopy. It’s a good way to do periodic checks for bowel cancer, but doesn’t obviate the need for a colonoscopy.
Disclaimer: IANAD, I’m way overdue for another colonoscopy, and I have a FIT test kit that’s been sitting unused for months now. Did I mention that I greatly dislike medical “care”? 
* - ETA: It may vary by jurisdiction, but around here, Pico-Salax is available without a prescription but you have to ask for it at the prescription drug counter. IOW, it’s semi-regulated.