You poor thing. That sounds like hell.
But it is interesting that school say she is okay there. She could be using all her energy to mask there and then exploding at you.
Please ignore this if I'm suggesting the obvious, and forgive the long post, but it took me years to work out how to parent SEN DS2, so maybe some tips will help. Some things I found helped, generally:
Bring a small non-sugary snack to school at pick up time and some water or milk. If she has low blood sugar after the school day, it might make her more grumpy. A bit of energy could help.
Create a really cosy area for her to unwind in when she gets home from school or any other stimulating activity. Could be a chair with lots of cushions and a weighted blanket (or any blanket), favourite cuddly toys, favourite books, favourite show playing quietly on TV or soft music she likes in the background. Just leave her there to decompress for an hour. No demands on her at all.
Avoid processed sugar and refined carbs - they might trigger meltdowns. Go for slower release foods that don't spike her sugar levels: wholemeal toast and peanut butter rather than white toast and jam. (I know how fussy AUDHD children are with food, so this may not be possible.)
Pick your battles. Forget 'normal' for other kids her age. You can waste so much time and energy trying to expect your SEN child to act like other children. She can't and won't. It really doesn't matter. Obviously it matters massively that she is attacking you, and that has to be stopped, but what sort of things are triggering these rages? Can you get rid of some of your expectations? Can you let her choose/decide some things that would help her feel more in control?
It doesn't matter if she wants the same food everyday, as long as it's reasonably healthy. Or the same clothes everyday as long as they fit and are clean and suitable for the weather. If she wants to keep toys from when she was younger, let her. (You might tuck them in storage and dispose of them when she's forgotten about them but don't tell her and don't have battles about them.)
One magic trick I was taught is to agree with how they feel, but not their behaviour. It is very time consuming but it beats a meltdown. So if there's a meltdown about getting dressed for school, you say, 'I know! Getting dressed can feel horrible. You really don't want to get dressed. Wouldn't it be nice to stay in PJs all day? But it's a schoolday, and at school, people have to wear school uniform. How about: you can wear PJs as soon as you get home tonight. And you can wear them all day on Saturday?
Weirdly, that often worked. If it didn't, you might need to take time working out what the actual problem is: E.g. I can see you are VERY upset at having to get dressed for school. Tell me what you hate most - is it putting on your knickers or your blouse? (Then go through each item of clothing and if that is okay then she puts it on.) You might find the label is prickling her and needs to be taken out of a blouse or that she finds socks very uncomfortable and needs supersoft ones. Once you work out a reason for the tantrum by breaking it down into stages and asking about each one, you might solve some of the triggers with her.
She cannot be allowed to attack you. But until you get some support, trying to prevent the build up of anger that leads to these attacks, and trying to identify what she needs to keep her calm, might help sometimes.
If she does attack you, go into another room and close the door. Say calmly through the door: I don't let people hurt me. If anyone tries to hurt me I won't be in the same room as them. If you want or need me, be nice to me. I am nice to you. I don't bite you. So don't bite me. When you feel calm, come and say sorry and then I will come out and we can make tea/watch TV and be nice to each other. Do this every time. Tell her you don't let people hurt you and leave the room, closing the door.