Bad latch after nipple shield?

smile55k

My LO was a preemie, and we had to give her bottles in the nicu. With the help of a LC, we started BF at 4 days old using the nipple shield. Now she is almost 3 weeks, and I BF without the shield for the first time and it was painful. She was pinching my nipple very tight and not opening to take enough into her mouth. How do I fix a bad latch? I think it is caused by how she is used to sucking on the bottles and the shield, but it also might be that she has a small mouth still, or that my nipples are just not used to the feeling and haven't toughened up yet. Anyone have any experience in transitioning from the nipple shield? Thanks!