Small nipples help

My son is 18 days old and I have a Medela pump, the attachments they sent were to big so my husband ordered the smallest ones that we could find and its still to big. I tried pumping once and got 3oz but after my nipple was so sore I didn't want to nurse. I am trying to stay breast feeding but would love to pump so I can get a break too, anyone have any suggestions or been through the same thing?