You are at a difficult point, i think. Good luck!
I would like to recommend the CIO method. I know its really hard to do this, and to let your kid scream, but, i'm a believer. It will take more than ten minutes (at least the first time), and commitment, though.
Even if you do not want to go that route, I recommend the book 'Healthy Sleep Habits, Happy Child'
http://www.amazon.com/Healthy-Sleep-Habits-Happy-Child/dp...
because i think it does a good job of discussing all aspects of sleep, and what is reasonable, and what is a good schedule, but is not a really strict advocate of any particular method of getting your child to sleep. The suggestions also made sense and worked for me, and some of them work for both co-sleeping and CIO parents.
Anyway, why my recommendation of CIO? Well, i wasn't sure about it, but with my child i noticed that every time we went in there we amped her up more. I also noticed that by interacting with her while she was falling asleep (even if it was just holding her) prevented her from falling asleep deeply. We resorted to CIO because our only other alternative was to hold her non-stop all the time. (And she still wasn't getting enough sleep.)
Within a few days of putting her on a strict schedule with CIO to get to sleep, we had a baby who fell asleep on her own, easily, with sometimes fussing (not yelling), sometimes, none. She sleeps well, and for long hours, and is a happy kid.
Given our experience our friends tried this for naps with their kid, and she, too, switched from a girl who wouldn't nap to one who falls asleep easily for naps, on a schedule, naps for a couple of hours, etc. She also became much happier than she had been when they were trying to rock her to sleep for every nap.
The evidence and correlation is so clear to me, that i feel like this is a real technique worth trying. The fact that all the kids that i know personally who have had their parents do this became much happier and much better sleepers makes me believe that the few days/nights of painful crying are worth the end result --- for the kid even more than the adult.
FWIW, i'm still pretty hands on with my kid. I encourage her to be independent, but i pick her up when she wants it. I don't always go to her if she wakes up at night, but if hear the cry that says 'mommy' instead of 'fussy' i do. I calm her down, and then put her back into bed.