I feel your pain! My DD (now nearly 15 mos) is a very challenged sleeper, and always has been. Around the 6 month mark I thought I might lose my mind from sleep deprivation. Here are some things that helped me get through:
Don't have a clock in the bedroom - or, at least, cover it up so you're not staring at it every hour on the hour. For me that was a big mental help.
I agree with PP that your DS definitely sounds overtired. I would make his daytime naps a priority over everything else, and find a way for him to be getting at least 3 long (45-90min) naps during the day. Maybe he needs to be rocked/bounced to sleep in a sling/carrier? Or fall asleep in a swing? Or a drive in the car? For us it was (still is, actually) the cradle hold in a Balboa Sling, and bouncing on an exercise ball to get DD to sleep. When she was your DS's age it was admittedly difficult to stop everything and devote all that time to getting her naps worked out, but honestly, it was so much easier to be relaxed/happy during the day b/c she was not crabby anymore, and naps were not a battle (she to this day still wakes up no more than 10 minutes after being put down to sleep alone, no matter how "deep" a sleep state I wait for).
And for nighttime, when it got the hardest, I went to sleep with DD when she did at night - as in 7pm. And there were stretches of time when I was in bed literally for 12 hours, granted not asleep the whole time, but at least I was getting to relax more and ultimately get in more cat naps. Bring books, magazines, your laptop, ipod (can put a book on it as well) - all of those things kept/keep me entertaining when I am holding/helping DD stay asleep.
The Baby Sleep Book by Dr. Sears helped me a lot. There are some strategies that he offers in there; even if they are not applicable to your situation, you may find some "attitude" tips in there. For me, adjusting my expectations and priorities helped me tremendously. When I wasn't freaking out about all the other things I wasn't getting to do and just accepted that they could (mostly all) wait for this time period to pass, it was a lot easier for me to be patient with DD and help her sleep.
I do NOT endorse any techniques that Dr. Weisbluth advocates in Healthy Sleep Habits, Happy Baby (he's all CIO), HOWEVER, I think he has some great points about the amount of sleep necessary at each age, how long babes can stay awake at different ages, etc, so I would recommend checking out his book only for those topics and ditch his awful techniques.

Since you brought up the thought of nightweaning I will volunteer my opinion on that: I would not recommend that *at all*. Especially since it seems you have a challenged sleeper on your hands, I would not take away one of your best mothering tools at this point. You probably don't want to hear this, but there are so many more developmental milestones/teething bouts ahead in your DS's next 8-12 mos that are going to wake him up at various points, and you may find yourself wishing for the option to b-f to get him back to sleep w/out you having to get up out of bed to walk/rock/bounce, etc. Even if you can't fully sleep through it, I think it's more relaxing than having to get up!
It absolutely SUCKS to be so sleep deprived.

If you can book any day-time with a relative/nanny/sitter, etc, so you can get a stretch of an hour+, or maybe you always get to sleep in on the weekends, etc. In general reduce your amount of commitments, day time stresses, etc. I promise you that it DOES get better as they get older. In the meantime just be nice to your self and realize you are doing your DS a great service by gently mothering him! Hang in there and good luck!!