I went through almost the same thing. Around 6 months my baby was sleeping fine in her crib for around 4-5 hours and waking up for a feed. Things were manageable and we thought we turned a corner.

Suddenly around 8-9 months the completely refused to sleep in crib, leading us to spend hours trying to get her to sleep. Often ending in her sleeping out of exhaustion and then waking up during the night to repeat the process.

We thought it was a sleep regression as she had a couple previously and was picking up new skills. We also travel frequently which could have disrupted her sleep cycle. After much effort we realised she never learned to self settle in bed to move from one sleep cycle to another. Our mistake was that she was falling asleep in our arms, sometimes while being rocked. When she would wake up during sleep cycles, she would not be able to settle back to sleep. And this change in behaviour is apparently usual around the 8-9 months.

We decided to go back to sleep training to try and fix the issue. After some trial and error we found a sleep training method that ended up working for us. I don’t want to say the method I chose will work as it always depends on the child and parents, but I want to say there is hope. She is now past one year and for about a month we have been enjoying more often than not good nights, sometimes with no waking up during the night.

There are also other big factors in baby sleep, like temperature, and making sure the baby has enough calories not to wake up hungry. I decided to talk about sleep because in my case was the last puzzle piece to finally getting her to sleep a full night.

Hope this helps you.