My 1 month-old just learned to latch well enough to meaningfully breastfeed with a nipple shield (we'd been doing primarily pump-and-feed prior). After a few days of mostly breastfeeding, I noticed some pain, and the left nipple gets creased/compressed and right nipple is lipstick-shaped after he comes off. I've tried many positions and many re-latches, the "breast sandwich" and "lower-jaw-first" techniques... Even with a good initial latch he eventually slides back to the base of the nipple. He's getting plenty of milk, but the latch is clearly wrong. Should I allow him to keep feeding with the bad latch and hope it straightens out as he grows? Or should I take him off the breast (shield) every time I notice a bad latch? Is the nipple shield the problem?