Ok so I decided to be brave and finally attempt to use one.
I bought one a while back a meluna but the material feels really weird and it's almost kinda misshapen.
So I invested in another. Well another 2 actually ( 3 tbh as one was a twin pack with both sizes)
So I went for a ruby ( recommended after that quiz) and a lena figured that gave me a choice of soft and a firmer one.
Well i figured I'd have a trial run today ready for when i really need it. Well i managed to get it in ok. Put it low as suggested but on the ruby I could feel the grip rings which made it feel a little weird and thank God I hadnt cut the stem off cos it kinda went a but high well actually they both did and I struggled to get them out 
I could feel the rings and the stem on both
which made it a little uncomfortable but I darent chop the stem off or I'd never get it out again and I'm not sure if removing the stem would even be worth it as I can kinda feel the rings too?
And both ( the lena slightly more so) well there was a bit of pressure not quite making me feel like I need to pee but almost.
What am I doing wrong
A already have three do I need a 4th?