Thankyou so much everyone for your replies; it's invaluable hearing your experiences and views.
It's such a relief to finally 'talk' about this. It's as though I've been holding my breath for ages without realising.
CoteDAzur I don't know a lot about Aspergers syndrome to be honest, it's mainly that she reminds me so much of my nephew that put the idea in my mind. I have an older daughter who shares none of these characteristics.
I'll try to describe her (possible) symptoms though (some of which might not be symptoms at all but would appreciate clarification on if anyone knows):
She had an extended biting career, during which she would bite people randomly for no apparent reason. She still bites sometimes, but only in a struggle; I view this as an improvement (don't know if this is related to AS but nephew was same)
She's pernickety about certain things, eg will insist that her blanket is completely straight and rumple-free. Insists her sandwich is cut into 10 pieces then consumes them in order
She talks in an odd voice, deep and flat-toned. Often with a West Country accent (she's never met anyone with a West Country accent)
Her vocabulary is very precocious. Her concentration span is amazing; she can sit patiently and draw or do pretend writing for ages.
She talks constantly, asks questions all the time, often when she already knows the answer. It's like she wants to have things constantly reaffirmed.
She's socially..I don't know how to describe it, but she'll go up to a kid in the park and grab their hand and say "Come on let's go down the slide!", and the kid usually pulls away and looks suspicious and keeps their distance She has some friends, but they are all family friends I suppose.
She has a fiery temper and is easily wound-up by her big sister. She screams and shouts and bangs and I find being confrontational in any way makes her worse; sometimes she just needs some space.
She is really sensitive to sounds and smells, noticing smells that I wouldn't.
Her physical co-ordination is not great.
She seems to enjoy the idea of other people being naughty (not sure this is an AS trait?) Nephew like this too.
She gets called 'a character' and 'quirky'. Ditto nephew when her age.
There's probably more but it's taken me ages to write this so I better leave it for now