Update:
So I tried the diamond fold while sitting on the toilet. I was not able to insert the whole cup in because when it was half way in, the latter part just want to pop open and my fingers aren't strong enough to hold the cup in shape. I tried a few time then went back to the triangular fold. The cup went in but it was flat and suctioned to the cervix.... I spent a lot of time to remove it and I couldn't...(a little anxious). But, I thought I should just go make dinner first and came back to it later. I was able to remove it later, yay!!! But my stomach hurts afterward XD I also found out that my cerivx was 2 knuckles in with my middle finger. Maybe I should get the small iris... but would it be as hard to pop open as the large?