Mom of 3, welcome to Healing Well!
I had the exact same problem in the beginning, and here's what worked for me. I ordered a larger size wafer, and cut the hole to the left of center, so that when I put it on my skin, it moved the wafer to the right and farther away from my belly button.
I shave all of the blonde hairs off around my stoma, so I don't pull them out one by one (ouch!) and do not use skin prep either, since it is built into my wafer. I have also had good results with the Coloplast Assura Extended Wear wafer. It's the Energizer Bunny of wafers, because it lasts and lasts and lasts!
I just put some Stomahesive paste around the opening of the hole that I cut, and press it onto my skin, holding it down for about 30 seconds to warm it up and get a good seal.
Since I get a good seal, I have not have any leakage problems nor do I have to cover it in the shower. Some people use Glad Press 'n Seal to cover their appliances in the shower.
Hope these tips help!
Dx'd Crohn's in '99 at 28. Proctocolectomy and ileostomy in '06.
Disease-free, medicine-free, and very thankful to be healthy again :)