OMG CUP USERS PLZ HELP MEH

MY CUP WON'T STOP LEAKING. I've tried everything: pushing it up farther, pulling it down lower, and I know for a fact that it's open all the way... UGH, idk what to do. It sucks because it works 50% of the times. When it does work, it's great. I can't feel it, I don't have to worry about it for 3-6 hours, it doesn't leak. But the other half of the times, it leaks. A lot. I still can't feel it, and I make sure it's fully open every single time I put it in... But it still leaks to the point where I still have to where a pad as backup everytime I use the cup... :(

Please let me know if you know what's going on or have any ideas/tips, any help is greatly appreciated. <3 ;-;