Oh, you poor thing - my DS was a terrible sleeper at that age. It's just mind-shattering being so sleep deprived and not seeing a way out. He's still not a brilliant sleeper (he's a night owl and 10:00pm is an early night for him), but at least he's not waking once he's down. We got to a point where he'd rarely be down before midnight, and usually it was later, and he'd wake every hour and a half or so. Sometimes he'd resettle quickly, other times it would take an hour. He was lucky to get 6 hours sleep in total a night, and that was heavily interrupted.

His problem was that he was rolling into the cot, waking himself fully, and freaking out. It got to a point where he would go ballistic even if I put him in his cot for a few minutes during the day, he'd developed a real aversion to it. So we put a double futon mattress on the floor, surrounded it with foam tiles, and his sleeping improved straight away. He still doesn't self settle (he's fed or rocked to sleep even now at 17 months), but he sleeps about 8-10 hours a night.

Not sure if this would help you or not. Have you read 'No Cry Sleep Solutions' by Elizabeth Pantley? It has lots of tips for different circumstances - it might help you find a way that works for your circumstances.

Good luck!