DS was like this - I can offer light at the end of the tunnel as now, at 11 months he sleeps much better - BUT..and I know it's tough, we did do some sleep training. We never actually left him crying for ages, but we did try and see if he would settle with a bit of shouting/ rolling around.
The advice we followed was from the Millpond Sleep clinic - there is a book - you stay next to them patting/ shhing/ singing but you don't pick up out of the cot. It's not very nice, as they do roll around and get hysterical, but it worked - he fell asleep the first night after 15 minutes which isn't that long and we hadn't left him. After this happened twice in the first part of the night he slept for SIX hours - an incredible improvement.
I really do believe that no matter how kind you want to be, they won't sleep well until they learn to settle back to sleep on their own when they wake briefly at night.
However - I am not a hardcore sleep type, and we did lots of back and forth picking up, rocking, mixed with not going in and letting him cry for 5/10 minutes sometimes - and that also worked .....
teaching him to fall asleep on his back in the cot did work - as did not going in immediately when he cries.......
also - I found that some sleeping next to his cot worked - made a bed on the floor next ot it and when he woke I would keep my hand in the cot stroking etc, it did help cut down night feeds. I have to say.....cutting night feeds saw a massive improvement in his sleep...not perfect and not entierely predictable, but much much better.