Either hospital grade pump is fine. And make sure your horns are the right size. Pump every 2 hours. Yes, this is a drag. But when a mom is essentially relying on a pump to maintain a milk supply you have to pump. A lot. Aim for 120 minutes of pumping every 24 hours. This means you must et up at least once between midnight and 5 am. Once he is able to nurse better, you can start backing down on pumping and slowly cut that out.
Keep trying to latch hm on, even decide to finish each feeding at the breast. This keeps his interest in breastfeeding up, or you will be trapped into EPing.
I would look into the TT again, as it isn't unheard of for it to need a second clip.
Don't give up hope. There are several mothers who have had a lot of trouble and survived.