Q&A: Menstrual Cup

Hi Ladies,
I've heard a lot of praises about the menstrual cup, and I'm ready to give it my fair shot. I'm hoping we can all use this as the "cup platform" to discuss with. Pads, and tampons especially, are just too harmful to our bodies and environment anymore. Let's take back control. 
Personally, my question is about sizing. I've read that the Diva is overall the largest model out there, Lunette is smaller, still great build, but the easiest to place, with best customer service is LENA. I'm leaning more towards LENA, so if anyone could share their experience with brands and sizing, even if it's not that particular brand, it would be helpful. I'm 19, never had children, or sex (engaged girl in white), been using super+ tampons for the past couple years, and I've got a heavy flow due to endometriosis. My worry is that the small size is too little for my needs. 
If you have any questions or just want to share your experience, please do! Let's make it a discussion.