Yes, mummytopebs, she is young anyway, but what you have to show is that your DD requires care that is above and beyond the care of a NT/well child of her age.
So for example, all children of her age have tantrums. BUT, your DD (IIRC) has rigid routines. So:
-What do you HAVE to do?
-What happens if you don't?
-How long does the meltdown last?
-What form does it take?
-What do you have to do to calm her down?
-How long for?
-How often does it happen?
-How does it differ from a typical child of her age?
Giving an example that you have used on MN, you could say:
"DD has very fixed routines, and finds it very hard to alter them. If we have to break the routine for any reason, she becomes extremely distressed, and cries, shouts and screams. For example, she has been attending afternoon sessions at nursery, and has milk. When she changed to all day sessions, the milk was given in the morning instead. DD was so distressed by this that she had a prolonged emotional outburst, and was still very distressed when I arrived to collect her. She was unable to understand that there was only one portion of milk, and that she had had it in the morning. I had to do x, y & z to calm her which took x minutes, before we could go home. A typical 3.9 year old would be able to accept that there was no milk left and would drink the alternative provided. A typical 3.9 year old would be able to adapt to changes of routine without getting very distressed."
You really have to spell out, from what I have read, the impact of her issues, and what it means in terms of time, supervision and care.
Having said all that, we have only just sent our forms off, so my advice is not tested - we may have a similar post to make in a few weeks!