Engorgement & supply question

So my son is 5 days old, and he has had a bad latch from the beginning..but I kept at it hoping it was just a learning curve we needed to overcome. I would nurse every 2 hours even though it hurt..& tried all the tricks to get him to latch correctly. My milk came in the other day and since the latch is bad..it's caused crazy engorgement. His pediatrician confirmed what I figured was the case, he has a tongue tie. Unfortunately I can't even make an appt to correct it til Monday since everything's closed on the weekends. Until then, I have to supplement and pump..along with continuing putting baby to breast so he sticks with it once we resolve the tie. I pumped today and from both breasts combined it was pathetic lol..it covered the thinnest layer at the bottom of the bottle. This was done about 2 hours after my son nursed. How should I continue to go about this to get a good supply without staying SO engorged?. I massaged & used a little heat for a minute before pumping..and I still feel SO full..but nothings really coming out..I don't get it. 😕 What worked for you if you were in this position??