post-pregnancy use

Hi there, I have a diva cup that I used for a few cycles before I became pregnant and it worked quite well.  Now this is the first time (this is the second post-partum period that i've had) that i'm using it after having my baby, and i'm having major issues. it keeps leaking (badly, so it must be completely in the wrong place), and seems to move around.  I have the larger size cup.  any suggestions? perhaps i should switch to a different type of cup?

thanks very much!!