Hello, I'm going through the same thing with my LO (10 weeks). She started to nap for 45mins then her naps got shorter and shorter until she wasn't able to have any day sleeps at all and it really affected her night sleep
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(this was after being admitted to hospital twice so her routine completely went out of the window). We've been discharged now for two weeks and I managed to get her to nap for 10mins as and when I could and have extended them to 45mins. We're now at a stage where I'm now extending them to 90mins which is thankfully working and shevis starting to have colour back in her face!
I extended her sleeps in my arms (I know its not ideal but was the only way to get to her each time she stirred). So I did the wind down until she fell asleep and each time she stirred I popped her dummy back in and did the sshh pat again until she fell back to sleep - her body fought it at first so I added in there a walk to calm her down before doing the sshh pat and just kept going with it until she goes back to sleep. Its taken quite a lot of patience and we've blocked out the last few days to work on it but she's now able to sleep again
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I will be working on her sleeping independently as soon as she manages to sleep for 90mins without support.
Anyway I just wanted to let you know that you're not alone and that I know exactly how you feel!