Oh purple you sound exactly like I did with my DS! He had a tongue tie and it wasn't spotted properly until he was about a week old. He couldn't latch and was getting very stressed out and frustrated. My nipples were agony, bleeding and I still have the scars! The problem for me was because he couldn't get his tongue over is bottom gum it was like razor blades digging into my nipple. Definitely push as much as you can to get the tongue tie fixed as quickly as possible. DS's was only very slight but it made an immediate difference to his latch and once it was sorted I breastfed until he was just over a year old!
While I was waiting for the tongue tie appointment I expressed a lot to give my nipples a break and breastfed him when I felt I could take the pain. It was absolute agony but I persevered. I used the tommee tippee bottles as the medela (I had the medela swing) he couldn't get anything out of.
Also he's only 4 days old and I think it was about then that my milk finally came in. I was topping him up with formula from a cup at that stage as he seemed so hungry and just wouldn't latch. It won't hurt him and if you keep expressing then your supply will continue to increase.
I really hope you get his tongue tie sorted asap as I expect that will solve all your problems. It's horrendous, and so awful to see your baby go through it, but it's over very quickly. They don't use anaesthetic as it would be more stressful and painful for them to have the injection than it is to just snip his tongue tie. Then they gave me a private room to feed him and he latched perfectly straight away, he knew what he needed to do and was fine, tears stopped within minutes. He still has a very slight heart shape to his tongue, but no problems now 
I say, I think he was about a week old when a new midwife saw him and agreed that it needed to be looked at. And it only took a week to get him seen by a consultant who did the procedure there and then. Good luck and feel free to PM me if you want to 