Hi there, I know exactly how you feel. I held Charlie 24/7 (that's how it felt) after about 4weeks & it was driving me insane, each time I'd pop him into bed he would wake up & scream. Many tears when DH got home from work!!! I borrowed a book from a friend called "Save our Sleep" by Tizzie Hall & I highly reccomend it!! I was able to realise much easier when he was tired, often he would cry & I would just feed thinking that's what he wanted...no wonder he's a big boy LOL. It really saved me, what you have described above is exactly what we went through & I was very embarrassed when I went out with other Mum's as I held him all of the time & when he got overtired he would scream & not settle.
We just perservered with putting him down each day & walking out of the room...some days he wouldn't last long, but before long he knew what it meant. We also added music & that seems to calm him. I would do this the same time each day & from this I was able to tell by when he fell asleep how long he can stay up before he starts getting tired, this has helped me to capture his tired signs.
It is very hard the first few weeks....big hugs. I've only just got to a comfortable stage going out & am only just starting to think I could do it again, one day.