One thing I love about this board so much is all the different LOs at different ages and stages. So quick question, when did your LO start sleeping through the night? L is 15 months old and was reliably sleeping through the night around 13 months (5 out of 7 a week), but a spate of teeth, travel and sickness has really thrown off his schedule. He normally goes to bed between 7:30 and 8 -- we lie in bed with him until he falls asleep most nights -- and sometimes wakes up crying a few times before we go to sleep around 10:30/11. That doesn't bother me, we just stick a paci back in his mouth and leave the room. But recently he has been waking up at 4am too and one of us will go in there and sleep with him until 6/6:30. Should I try sleep training again? We did Ferber around five months and that worked for a week and then he got sick and we stopped doing it. Shortly after that is when we found out about his gross motor delays and I guess I've just been loathe to force him to do anything related to sleep.

Re: STTN?
That said? She went through weird stages that started around 12 months old. All of a sudden, she started waking in the middle of the night. She would do that for weeks, and then go 4 months and not wake. Then she would wake again for a month, and stop, etc. For her, they were always just stages. It actually continued until she was like 4. She would get sick and wake in the night, then get into that habit of waking and keep doing it and call out to me. But then she would go months and not do it.
At almost 8, she will still call out when she's sick or has to pee. But I don't really count that. Once she feels better, she will sleep from 8pm-6am. But she absolutely went through weird sleep stages. They always ended, though, and I changed nothing.
MMC 3.30.16
He slept in his crib from the second week as he was soooo loud he kept me up.
My DS is 22 mo and mostly sleeps through the night, but that has only been for a couple of months, maybe 3. He has always been a terrible sleeper. We sort of followed the Sleep Lady Shuffle around 13 mo (but we stayed by the crib for reassurance, didn't leave the room) and that worked for awhile, except he would still wake in the early morning to nurse. I think I should have night-weaned him completely at that point, because after a couple months of that he started waking more frequently again and our previous sleep training methods did not work. We muddled through and managed to night-wean him around 18 mo and since then he usually STTN. If he wakes now I know he needs something (I give him a few minutes to resettle himself before going in).
I don't think you're necessarily "doing it wrong". There are so many ways to approach sleep training or coaching, and every kid is different (from month to month even!), and every family is different. I do think part of the reason my DS finally started STTN is just developmental maturity. There are things you can do to nudge one way or another but you can't make anyone sleep! Some kids will just get it on their own but some do need more coaching.
I am rambling, but I hope that was somewhat helpful.
But we are at 3 years 2 months, and he still wakes up at least once a night for a hug, water, potty, whatever. Last night he woke me up three different times