MermaidCup?? Size??

Has anyone tried this??? I’m thinking of getting it but looking for reviews on it.

Also having trouble figuring out what size/firmness to get of any cup. I’m 27, had a vaginal delivery and a high cervix. I do hiit 3-6 times a week. The first day of my period is the heaviest but half way through the day it mellows down quite a bit. Any suggestions or tips would be helpful.