Lea it is nice to see you !

I've
: tried getting up earlier, and that
: seemed to be working,

but then my
: original pattern reset again,
: after being stressed and not
: sleeping, being awake until 5 am
: in the morning. But I still wake
: at noon.

looks like you have had some success there. First thing that came to mind is how summer is so different for me from winter, so if you are having a play with sleep patterns, a good time to have a go!

perhaps getting up even 10 minutes earlier would gradually ease you in. Are you able to have a snooze in the afternoon if you get tired?