For starters, the only stupid question is the one that isn't asked!!
Secondly, I haven't had a leak in public in over 19 years, and I'm a VERY active guy! Most leaks occur in the beginning, and are almost always caused by the person and not the appliance. Either the appliance was left on too long, or wasn't applied correctly. In the beginning we're not exactly experts at changing our appliance. You should expect a leak or two until you really get the hang of it. It really is trial and error for a little while.
But, what you're feeling is quite normal. Once you've had the surgery, and you're out and about, you'll start to realize your worries were unfounded.
Plus, who wants to wear a diaper? Not me!!!