Hi! Who uses menstrual cups? Explain to me how to insert the cup so th…

Hi! Who uses menstrual cups? Explain to me how to insert the cup so that it doesn't leak? I've tried every way! I have two sizes of cups. The small one doesn't open up in me. The big one opens up. I insert it tightly until the end. But it still leaks! I spent 700 rubles on these cups, is it not worth it? For the second month I'm struggling and nothing works ? What am I doing wrong... Maybe I'm doing something wrong because it leaks. Or maybe the size isn't right?