cup width question

Ok so when I started using cups I started with the diva which as I've said in previous posts made me extremely crampy to the point where I couldn't stand to have it in at all. So I bought a shorter cup, which as you know is the now damaged M meluna. Before receiving the meluna I was worried about the larger rim, but it seems to work just fine. Because of said stem problem with the meluna, I am thinking about getting a lunette. I don't know whether to get small or large. I like the larges rim size but dont want a gargantuan cup. Also, I'm wondering if the smaller rim of the diva somehow contributed to the immediate cramping, as well as the length. Not really sure what to do. I may try re inserting the diva to see if cramping ensues again. Anyone have any thoughts on my rim theory?

I love you ladies, you are always so helpful with my questions!