Drying up? ๐Ÿ˜ž๐Ÿ˜”

La
I am so frustrated. I planned on exclusively breastfeeding my son but have run into constant issues.ย 
It began with him not gaining weight in the first two weeks. His pediatrician diagnosed him acid reflux because he would sometimes gag while trying to bf and put him on Zantac.ย 
I decided to get a second opinion because I did not believe he had acid reflux at that time. So I went to a lactation consultant. She found that he's not latching correctly and showed me how to try and get him to latch correctly. But she also said I needed to start supplementing because he was not gaining weight like he should be. I also started taking blessed thistle and fenugreek, the consultant said I should have noticed a difference in my supply within a week; which it didn't make much difference. So she told me I could discontinue using the herbs.ย It is very upsetting for me because I never had issues with my first son. I have also tried drinking the Gatorade to help but that hasn't made much difference either.ย 
At this point I am only getting maybe an ounce from each side, sometimes more if I don't try to bf him. My question is, is there any way to get my supply back up with pumping? I have come to the conclusion that I will most likely have to supplement but I would still like to be able to give him breast milk as much as possible for as long as I possibly can since it is so much better for him.ย