I was deciding on the soft Meluna in a small but someone told me on here that it might be too small and not hold enough since they tend to be pretty tiny. My period only lasts 3-4 days but the heavy days seem to be pretty heavy so I'm about to order the medium soft Meluna. I had to take the plunge sometime and this has been the cup that seems like it would be the best for me. I've been researching for about a month.
When wearing tampons I'd usually have to change a regular size every 3 hours or something like that. I think 20ml for the medium is a good amount so I can go a while without having to worry about emptying it.