I have a PISA and EP. I currently have the biggest size shield that Medela makes, but I'm not sure if it's quite right. I know that one of my nipples is little flat, so it fits differently than my other one, but it looks weird in the shield while pumping, like it's still not big enough. It's uncomfortable while pumping, but I also had to wait a few days using a smaller size while the bigger one came in the mail.

Is there another brand I should try using? Is it just the way my nipple is and that's why it's weird? Am I just being paranoid?