So I'm finally on my period and using my Diva Cup. I thought I had it in there okay, but apparently it's not sealing, so I've got just a little spotting. I tried to turn it after inserting it, but I can't get it to turn. :/ All that happens is the base twists in my fingers, but the rim doesn't budge. I can't get my finger in far enough to test the seal. Any suggestions?