DK Smoothie Cardi

I spent this afternoon looking for buttons for my DK Smoothie cardi but I have to admit to myself there's a big problem with it.

The neckline is too loose and any button that fits, looks too small and they don't hold it tight enough so the neckline just keeps stretching across my shoulders. It's also quite weighty fabric so that doesn't help.

I think I will have to either try a clasp instead of a button and/or sew some tape/binding along the neckline.

mmm... I'll put a photo up and maybe you can give me some suggestions.