I have similar troubles and posted about it here: (where you'll find more similar experiences and strategies)

https://www.bellybelly.com.au/forums...please-175158/

I've just let it go, as all the re-settling was only yielding a very occasional longer sleep, did not teach him to sleep longer independently and was ultimately just stressing us all out. I'm still exhausted and would still love more down-time, but happier for just letting it be for now, with the hope that longer naps may one day eventuate. Good luck!