While I agree with the above opinions, especially that the difference between real life and the game is that we can't actually die, your patrol is not entirely unrealistic. There were 21 real-life patrols more successful than yours, so it did indeed happen.
http://uboat.net/ops/top_patrols.htm
On the other hand we don't really play Dead Is Dead, no matter how much we claim to the contrary. You want to really play DiD (without actually dying, of course)? Try this: If you die in your campaign, put the game away and don't play it again for a year. You'll be much more careful after that.
