I have 4-6 day periods and I would say a medium flow (I change a regular tampon every 2ish hours). I am still a teenager and I have had sex but only once (don't know wether this would make a difference or not). I have checked my cervix and I can fit my finger in the whole way and still feel it. I am fairly active but don't do too much sport.
I was thinking about buying a classic resistance Me Luna in either size Small or Medium, but I'm not sure which is right. Any other brands and sizes that you think would be more suitable would also be appreciated.
UPDATE: Thanks for all of your advice, it has really helped! I have been doing some more research based on what you have said and I'm thinking either an iCare small or a Lunette small but I'm not sure which to go for as they seem pretty similar. Anybody that has worn both of these cups that could give me any pointers would be great. (I did look at the Si-Bell cup as many of you recommended but I was worried that it would be a bit too soft and I could not find anywhere that would ship it that was in stock)