Hmm, if she's still hungry it's fine to offer the second breast. My daughter had reflux but Zantac helped tremendously. Have you tried meds? I'm wondering if oversupply is your problem. You mentioned eliminating dairy. How has that been going?
I understand how frustrating this is for you. You just want your baby to be well and you're trying a million things and nothing is working. Definitely see the LC and maybe see if you can find a pedi who has experience with breastfeeding to also help you troubleshoot.