The sarcastic answer to your question is......you'll be comfortable with dating when the person you're with finds out you have an ostomy and doesn't bolt out of the room screaming 'Holy crap...what was HE thinking!!". And when that does happen.........you won't be comfortable anymore.
Seriously, there is no good answer to that question, as I'm sure you're really aware. But you eventually have to test the waters or get used to being alone. And it might not go so well when you try, but nothing in this world worth having ever comes easy. Eventually you'll get to the point where you're comfortable in your own skin again regardless of what others think, and then rejection won't sting as bad. And the longer you wait the more f&^ked up the rest of the dating population becomes, as no one dies healthy. So the younger you are........the less understanding for your condition others your age will have. Experience equals wisdom..........so go get you some!!