Moon cup size?! πŸŒšβ˜•οΈ

Lola πŸ’πŸ»πŸ’• β€’ 21 πŸŽ‰ Not ttc, been with my partner for over 2 and a half years and adore him πŸ’• mummy to 2 furbabies🐱🐢❀️
Ok! After months of being sceptical about these menstrual cups, I have been convinced to try one based on people's glowing reviews on them. 
My questions are;
1.) boots do two sizes, size A and size B. I've never had children and I'm 21. Should I  probably go with size A?
2.) has anyone tried other brands like the American diva cup or other uk cups in comparison to this one and found one much better? 
It's not the cheapest thing on my wage so if anyone has any thoughts that be really appreciated. Thankyou all! πŸ’•πŸ˜˜πŸ‘ŠπŸΌ