I too was recently in MBU for PND and help with settling. I initially was going to only stay 1-2 weeks but ended up staying 5. I was really hard at the time because like you I missed my partner, I felt guilty for being there and separating our family, I wanted to return to reality so badly but deep down I knew I still needed more help with DD. Looking back now it was the best thing I ever did and would do it over if I had to. You don't wanna go home to soon only to fall into a pit again and undo all the hard work youve already done. Your DD will adjust very quickly to going back home, the first day my DD was a little unsettled because it was a 'new' environment for her again but they are very adaptable.
I wish you all the best