What should I do about my partially closed navel piercing?

I got my navel pierced four years ago, but I haven’t worn a navel ring in several months after my last one fell apart. Today I tried to put a new ring in, only to find that the hole appears to have shrunken. I can’t fit a standard 14-gauge navel ring in it, but I tried the thickest embroidery needle I could find (which looks about 18g—don’t worry, I was careful and didn’t insert the needle pointed-side in!) and that was able to go all the way through.

I’d like to start wearing navel jewelery again. Should I try to find a ring that’s a smaller gauge or try stretching out the hole slowly? Is it even possible to get navel rings that aren’t the standard 14g?