The thing you said about him wanting to be held in a weird position struck a chord with me - as my DD was like this too and was a shockingly bad sleeper - Is his reflux now under control? because reflux (whether its silent or spewy) can cause all of what you are describing. My DD is still on losec at 22 months for silent reflux and I have always found every routine, book, info I read just made me more stressed as they never worked for me DD. The only times we have been able to get more sleep and a bit of a routine was when she was on the right medication and the right dosage.
My heart just goes out to you, because reading your posts is like a mirror image to how I felt not too long ago.