My 4 week old just began nursing with a nipple shield (we've been pumping because she refused the breast- even with a shield up until now) She's nursed three times, but two of these times have been very painful, and when she comes off, my nipple appears pinched! I take care to make sure the shield is centered, and I was fitted for my shield by an LC, but two different LCs gave me two different sizes! Any ideas on why it would be so painful??? I was so excited she's nursing (I'm sick of pumping), but now I'm worried we may not be able to keep it up. TIA!