[Excellent questions you posted Ken
Hello centurion77, Welcome to the forum.
How do I post pictures?
I am short on time at the moment so please read this:
There is a link near the bottom that re: Gnomes tutorial on posting pictures though you may find the entire thing helpful.
I bought it at a large surface greenhouse store this summer, like an idiot I watered it with tap water and filtered tap water,
'like an idiot'...
Why do you say that? I sincerely
doubt that is a factor in this trees condition.
BTW, I use tap water all the time, I just let it sit for 24 hours first so so any residual water treatment chemicals can evaporate.
I bought Bonzai liquide fertilizer which I vaporized on it one every two weeks until two months ago (when the new green shoots withered and died..)
As I read this with your watering schedule below you are feeding nearly every time you water?...
Is that correct? When you combine this with your compact [practically non-draining] soil I expect you have a large amount of fert/salt built up in your soil. Quit the ferts for now.
EDIT: Sorry just noticed you were misting the ferts on, I would still quit them for now.
FYI - Except for the label [& possibly the price], There is no discernible difference between 'Bonsai fertilizer' and any old regular balanced fert.
The soil is the one I got it in, it's compact and I keep it moist (water about once every two weeks).
Considering how long it stays wet...This sounds like EXTREMELY compact soil
[Which is NOT good btw - Please read the stickies at the top of the forum referencing 'bonsai soil']
I have to keep it inside, I put it on a bookshelf facing a window (most sunlight available)
It's winter here and my appartment is old, so the heating is on all day (The heater is about 2m away).
I hope it's just dormant.
It is most certainly NOT going dormant inside...Something else is going on - Possibly a lack of light [amongst other possibilities IE: Soil & watering] from the sound of it.
Here are some articles you should check out, This entire page is full of them: https://www.bonsai4me.com/Basics.html
This one is also: https://www.evergreengardenworks.com/articles.htm
Here is a care sheet for your species of tree: https://www.bonsai4me.com/SpeciesGuide/Ulmus.html
More later & I am sure others will chime in.