Calling all menstrual cup experts, I need some help!

So I just got my first post-partum period. My last period was Sept 2017 so it has been a while! I use a Diva cup size 1 and the first 1-2 days it worked great! Was really easy to put in and no leaks. On the evening of day 2 it started leaking and now it's like it just won't stay in properly. I ordered a size 2 so I'm hoping that will help the problem. I also can tell that my cervix is much more posterior now that I'm a few days into my period and I have a retroverted uterus so that could be part of it.

Any suggestions? Do you think the bigger size is the answer or is there something else I can try?