My other problem though is that as well as night time sleep changing at 12 weeks, so did her naps. She only naps for around 30 minutes at a time no matter what I try
There is a change that happens to the physiology of sleep at around 3-4 months old. This is a perminant change, sleep will never go back to how it was. So this phase lasts as long as it takes you and baby to adapt and find sustainable fleet habits. That's a couple of days for some people, many months for others.
The first 3-4 months are often called the "fourth trimester". It's a continuation of the slerp structure that happened in the womb. So sleep in the womb is passive, so sleep in the first 3-4 months is passive. As long as all needs are met (hunger, comfort, security) then baby will be in the passive state of asleep. Baby then wakes as a need is unmet and once it's met, go back to sleep.
After this fourth trimester period, sleep matures and becomes an active endeavour. It now becomes hard work for baby to get to sleep, requiring active effort from you to help. This is because going to sleep is now an active state, not passive.
Sleep also develops into cycles with periods of deep sleep and light sleep and brief 'environment check' semi-conscious wakes between cycles. Therefore staying asleep is also an active endeavour.
Sleep will never go back to being passive, hence it's a perminant change. Some people will find a method that works to get baby to go to sleep and stay asleep quickly so this phase is short for them. Others will just wait and wait and no improvement happens.
That's the science. My suggestions:
- persevere with a settling method that doesn't involve feeding
- if you want baby sleeping independantly, start getting baby to go to sleep where he will stay asleep. Be that a bouncer, pushchair, in the cot. This is much better than moving an already asleep baby into the cot
- INTRODUCE A DUMMY. If you haven't already that is. Dummies are key to no crying independant sleep.
- linking sleep cycles is developmental. 30-45 minute daytime naps are normal. To avoid over tiredness reduce awake time. I would aim for 60m awake time at this age
90m at the very most. If it takes you time to settle baby to sleep, include this time I'm awake time
- sleep cycles at night are usually longer (more like 2h ish) and not unusual to need to resettle. The less over tired baby is, the less chance of waking between sleep cycles. Fast and effective settling methods can mean baby can resettle back into a deep sleep without properly waking up, which leads into...
- Don't assume baby is always hungry when waking in the night. That would have been the case in the passive sleep early months. But now, baby is more likely to just need some help getting back to sleep. If your only effective way to do this is feedibg then you'll end up feeding frequently through the night. Better to develop an alternate method.
- but night feeds may still be needed. Ensuring baby is very well fed through the day will reduce the need to night feed. Big feeds given frequently in the daytime with minimal distractions when feeding. This will 'calorie load' through the day.
- remember to wind well. Especially important at night when lying flat.