G.K.
I skimmed the other responses, but I really feel like what you need right now is POSITIVE encouragement!!! I went through the same thing with my son when he was that age, and it seemed that nothing I did changed his "sleep schedule." At his age, he wasn't even going to bed for the night until 4am!!! I was SOOOOOO exhausted! The upside is that it truly doesn't last forever, even though that's how you're feeling now! On the heels of that, please be aware of the state of mind that your exhaustion is creating. I know it doesn't happen to everyone, but I fell into postpartum depression and didn't recognize it, which made everything that much worse!!
As far as producing enough milk, it sounds like you're doing great! I mean, holy cow!! You can pump 5-8 oz/session!! That's AWESOME! As far as feeding length goes, every baby is different. It's not that he's lazy, that's just how he feeds, and that's OK!
I do agree with a few other posts about his gassiness being caused by something in YOUR diet. Pay special attention to what you eat in the hour or so before bed. Dairy (primarily milk) is usually the biggest culprit, but other foods like broccoli, cauliflower, and even green peppers can cause infant gas. I also had this issue with my son, and as soon as I switched from skim milk to Lactaid, things got SO MUCH BETTER!
For the most part, your son sounds normal!!! It sounds like things are going great, but if you have questions and/or concerns, feel free to call Nursing Mothers Counsel. We're here for mothers just like you, and we provide free one-on-one counseling. Feel free to contact me directly at ____@____.com or call our hotline at (650) 327-MILK. Congratulations on your son and your decision to breastfeed!!