I just want to breastfeed 😞

I feel very discouraged and depressed since yesterday after seeing the Pediatrician. I found out my LO has a upper lip tie which is what is causing me so much physical pain while attempting to feed, and why she isn't getting enough milk and falling asleep at the breast. I was suggested to either formula feed or pump exclusively... but I've noticed with pumping my supply goes down every day just a little more, and I know that baby does the best at removing that milk. I wish I could correct it, but I don't know anyone in my area that would. Not to mention if there is really anyway to work with my LO on a better latch. Is there any other mommies out there that have dealt with this or are dealing with this that can help?