Meluna cup is slipping down

Hello,

I have had my meluna cup for about a year. 

Over the last couple of months it has started slipping down when I am wearing it. I have a really bad cough at the moment and a couple of times I have almost coughed it out. Once it gets down too low it feels really uncomfortable.

It is a medium sized meluna cup. I am 39 and have had two babies. I suspect my pelvic floor muscles are not what they were so I  might need to go for a bigger size. However I also have a lot of trouble getting it to pop open, especially when it is already at body temperature (rinsing it in cold water helps, but I can't always do this eg in the toilet at work). So I'd like to try something springier. Any recommendations?

When I first got the cup I had some teething troubles with the cup — I had to cut the stem off as it was too long, and I also have to turn it inside out as there was a rough edge where I cut the stem off . So this time I would probably get one without a stem.

Thank you.