Go back to basics in how you position her. Make sure her back is supported. Plenty of boob in her mouth.

And watch her while you are feeding. Work out when she is most likely to do it, its often at the end of the feed when bub has had enough, and take her off before she clamps down. There is often a sign that it is about to happen.

Congrats for exclusively breastfeeding too! I admire those who weren't able to first time around, and manage to get it working next time.