Re: Shields too big?? & Soreness...
I use both the medium and the large size and alternate between the two because one breast pumps better with the large and one breast pumps better with the medium ( I don't like to mix sizes because then one side sticks out more than the other making one handed pumping difficult, but that is neither here nor there)
When I use the large horns my smaller breast gets a whitish ring around the nipple. No pain, but the ring sounds similar to what you describe, so perhaps they are too big, or maybe you need to mix sizes. I don't think there is an exact science to fitting these things as everyone's breast respond differently.
I know it stinks to spend $$ on things that you end up not using, but if you are going to be pumping a lot for work it is vital that you find something that is comfortable.
My little man was born 12/17/2010.
Baby girl was born 4/30/2014.