craft advice - grommeting thin leather

I picked up some thin leather on sale at the fabric store the other day and made a skirt and a bodice-thing. I was pretty pleased with it, except when I was taking off the skirt, I noticed two of the grommets I'd put in it had pulled out. They weren't under much stress, so I'm sure my other grommets are all in danger of falling out, too.

I punched the smallest holes possible to get the grommets through, but the thin leather seems to stretch open around them pretty easily. I'm planning to try folding over the leather so I'm grommeting through two layers instead of one, and then pounding a bunch more on the grommets to get them down real tight, but I'm concerned it still won't be enough.

Does anyone here have grommeting advice? Are there other good ways to put holes in thin leather that I can lace through?