Sorry to hear that things aren't going as well as we all hoped. Are you using the SNS at all? I know it's tricky but it might help get your son onto the breast more regularly... And don't feel like comfort nursing is wasted- even if the babies aren't getting a huge amount of milk they are getting some, and the comfort and closeness are very important as well.
You're doing a fabulous job!!! You really deserve a big pat on the back for making this attempt. Even if it only lasts a little while, it's still an amazing journey.