It is not very often I respond here, but I feel for you, so I share my experience. My mum's baby Bible was Dr's Spock book and she brought it to me when my baby was born. Dr Spock was a very famous pedestrian in his time, did give some crazy advises (like putting babies to sleep on their tummy, which led to cot death), but there were a couple of advises in his book, which I took on board and they actually did work for me.
You see, he did believe, that after 3 months old babies can be "trained" to sleep. Yes, the stomach is still very small, so they need to be fed every 3-4 hours, but after being fed they have to go to sleep again.
This is pretty clever advise, but how do you explain it to your baby?
Dr Spock believed that there are two sorts of cry one baby can produce: a distressed cry, and a capricious (sort of pick me up) cry. While you mustn't ignore the distressed one, you should pay no attention to the capricious one 
Once you start "training" your baby, it is going to be hard. My husband had actually to chain me to the bed, so I did not run to her with every her winge
.
So, imagine, your baby goes: ahem.. Ahem. Ahem! Aaaaah!
You do know they just have been fed and changed. Stay still. In a few minutes the baby will go ballistic. Pick them up, calm them down and go back to your bed. Repeat as many times as necessary. They will get your message eventually.
I wish you best of luck. My kids are 16 and 11 now, this was long time ago. I am very grateful to Dr Spock, his book saved me life, ha ha