Pumping on lower setting

Gi

Hey.

I am new to pumping and my nipples have been sore so I turned my pump down a level and I feel like I didn't get at much milk. Is this going to make my supply go down? :/ I'm just at a loss. I know some pain is normal but I'm in need of relief and this seemed to help. I just don't want to loose my supply over it. Should I pump longer?