That happens every now and then to everyone.
I meant to reply to you first, and got sidetracked, sorry.
To me, practising, as you did, even after leaving Spain is wonderful, and praise for keeping up.
I would try to reheat the motivation by easing it off, leaving Grammar for now, and watching and listening to a favourite topic in the goal language.
Figure skating, fashion chat, an interview with the spanish Queen, ( oh those would be mine
)... whatever you fancy...motorbike tour through Spain reportage...
And then pick 1 or 2 idioms and work them through, with the items that got you stuck, and trying to create 2 exemplar sentences to unstuck you...and that's it...for the day...it ought to make you feel victorious. To proceed...
There are paralells with music education, we all get stuck, as said, in the role of students, my students get stuck twice a week, at every lesson. But those are the diamonds that propell ( oh this does not look spelled correctly, apologies) us, or shine on us...a hidden treasure...
Muy bien ( Gosh, I know 0,04% what I am saying or writing in Spanish)