nazly the book is from this website sarahockwell-smith.com/category/babies/ and is called The Gentle Sleep Book. Her website and info is very against seep training involving crying so be aware if you're thinking of doing that. She's very for bed-sharing, I had a quick check of her book and she says:
"Many parents are concerned that if they allow their baby into their bed they will be creating a rod for their back and they will never get the child to leave. Rest assured, your child will soon be independent enough to move of their own accord, often at around 3 or 4 years of age, but many babies happily move to their own bed much earlier than this. If you are not keen on sharing with a toddler or preschooler, a good age to move a baby to their own room is around 6 to 8 months, when they have passed the fourth trimester and four and five month sleep regression but not yet hit separation anxiety stage."
She goes on to say if you don't want to wait for them to leave then do it gradually, eg cot next to you, mattress on floor
I was very reassured by her book, as I cannot leave him to cry incase his reflux is bothering him and I was getting worried that I was mucking up his sleep for good. However she firmly believes that sleep is a development stage and that they'll get there in their own time and that they're incapable of true self settling until school age. Of course I hadn't really planned on cosleeping for 3 or 4 years 
but we'll cross that bridge when we come to it.
As for supply, I have no tips apart from what I've read about oats and fenugreek helping supply but unfortunately I think it's just a supply and demand issue. I know that people do continue to feed solely at night once their babies are older so there must be a way to do it, just no idea what it is.