I understand your struggles. Here is my way of explaining your struggles. I put it in quotes.

<pressure in my head - feels like my brain is too big for my skull >

I call these mud head aches. They make it difficult to focus because of the strange sensation.
" I have a almost constant sensation of pressure in my head that makes it hard to focus, sort of like living with a head ache."

dizziness

"I have bouts of dizziness. This makes it difficult for me to feel confident in movements, especially if I need to carry something that could be dropped or worse, land on me as I fall "

extreme sensitivity to bright lights and sounds

" I am hypersensitive to bright lights and sounds, especially multiple sounds. It makes me feel like there is far too much happening around me. This can make it near impossible to concentrate or lead to an anxiety like attack. "

my legs and arms don't feel right my legs feel like they're tangled up

" I struggle to feel confident in my coordination. My legs and arms feel confused. I often need to stop what I am doing so I can do just one task. It is like the old saying, He can't walk and chew gum at the same time. I can not multi-task with my motor skills."

loud sounds eg someone shouting makes me dizzy as does stress

"I am easily startled by or someone shouting. This increases my dizziness. Anything that increases stress levels causes this same increase in dizziness and loss of coordination."

I also can't really concentrate on anything

my memory is really bad and I used to be a really organised person but not anymore

I can't fill in forms properly

"If I need to fill out a form, my mind gets overwhelmed by all of the empty fileds that need to be filled in. It is like my brain feels the need to fill in all of the empty fields at the same time rather than methodically work my way through the form on field at a time "

fyi, I have a trick for dealing with this. Put a blank sheet of paper over all but the line you are working on. The filled in fields will not be much of a problem but the empty fields below will be a challenge so covering them will make it easier to visually process the form.

and if there's anything else going on (noise etc) I can't do it at all as I can't concentrate properly

" I am easily distracted by any ambient sounds or other activity. It pulls my focus away from the task at hand and may create a safety risk to me or those around me. "

Hopefully, I have helped you understand your own symptoms. You need to understand them before you can help someone else understand them.

My best to you.