I just recently got my DivaCup, and I tried inserting it for the first time this morning, but I haven't been successful yet. I'm having trouble getting it all of the way in before it pops open. I can get the top part in, but in trying to reposition my fingers to move it in further, it pops open too soon. I gave up temporarily because my vagina was getting irritated with me trying so many times. Any tips for when I try again later?