First time using menstraul cup?? Got a question...

So this is my first day using a menstraulcup and So far I had trouble trying to put it up there, but once i got the grip right it went in! I dont even feel it! But part of me is scared thinking its not sealed because i watched one vid that said they felt a suction up there but i didnt feel anything happen so could i have put it in wrong?? How do i know if its sealed so i wont leak??