Confidence is certainly something built up in time. I know that isn't what you want to hear, but it is true. Even a veteran gets shaken when a leak occurs out of no where. But, once you get your system down and learn from your mistakes and by others' mistakes, leaks become infrequent.
I, too, am a believer in Eakin Seals. And I don't use the whole seal - just a small strip around the stoma hole opening, as you would use stoma paste or the like. Do you use any of these products?
Yeh, any kind of oil near the flange is probably not a good idea as it can travel during a hot/warm shower. And, it's not something that you can really See or Feel to know that. Best bet, minimal oils on the abdomen as you know now.
As the days/weeks go by, you will gain confidence again and won't give going out a second thought. I know it is easier said than done!
Best of luck to you,
Diagnosed with CD in 1979, many resections and meds
Perm Ileostomy July 1984 at Cleveland Clinic
Disease free since surgery