There are some possiblities depending on how much needs to be added. If "it won't even go around me" means that the two ends don't meet, then you are probably not going to ever get it large enough. It needs to wrap around 1.5 times (basically).

If you need "some" inches, there are reconstruction methods such as using the underapron fabric to create more pleats, and adding a new underapron from a solid-color coordinating wool. The underapron isn't seen under normal wear, so you can steal from it.

There are many more experienced kiltmakers on this forum who (one hopes) will have more specific advice and perhaps other ideas. Whatever you do needs to be done by a pro who understands kilt construction, or you will end up with an altered, unwearable garment. Better to hang it in a display case than that.

Best of luck! FYI one of my nephews wears his great-grandfather's kilt which was remade to add the necessary inches, so it is not impossible nor un-heard-of.