I had the same problem, and I tried the crying out and it was always the wrong time, and I was so confused by all the books and advice. We have only just sorted it out and he is 20months old. I will tell you what we did.after 3 nights, when you are supposed to see some improvement I was still wondering whether if I was doing it right. But then on the 8th night,he slept from 8-7. I was astounded, and he has done it every night since... about 2 months.
It's really hard listening to them cry, but he is so much happier now, and I knew what I was doing would ultimately the best for him. Imagine how you would feel if you were up a couple of times in the night and didn't know how to get yourself back to sleep!! It's just a case of helping them to unlearn their bad habits. and they learn quite quickly.
Firstly, you have to be sure they are not genuinely hungry in the middle of the night. So need to make sure they have strict 3 meals a day, no snacks and not too much milk.
Then set time for bedtime/bathtime routine.It is supposed to help if they spend extra time playing with you in their room/cot, then after the last feed, you really should put them down awake.I think that's a difficult one, but I think it helps with the sleep association. then kiss goodnight and lay them down. then leave! You decide on how long you can leave them crying,say 5 minutes, then go in and check on them, if he's standing up, lay him back down, say goodnight, comfort a little, then leave again. However long you first left them for add 2 minutes,so 7 minutes before you check again, then 9 and so on.This was the bit I was unsure about as i am not sure they can really distinguish between 5 and 7 minutes!
Eventually they will fall asleep.When they wake up again repeat the process, starting at 5 minutes or whatever your first interval was.I found that going back in upset him more so it was easier to leave him a little bit longer. If you give in at any stage they will think that however long they cry for you will give in!! They are very clever.And I always thought if I give in now all of his crying will have been for nothing, that's what made me stick with it. Then you have to follow the same process for naps. Any change in the process will make them think there is a chance to get their own way. If it helps it is better to do it now, rather than when they are older and they are shouting Mama! Its heartbreaking.
The most he ever cried for was 15 minutes, so maybe i was lucky, cos you hear nightmare stories about them crying for hours, but I think if you go in regularly they are a little bit reassured. On the 7th night, we had a stand off and he cried about 5 times in the night for about a half hour.
It's exhausting but hopefully at the end there will be a good night's sleep for you all. good luck.
I really hope this helps!!
S.
x