Evita, there is a thread called "Worried/Aspergers?" on which Jimjams posted a very long message which is, I think, the best summary I have ever seen of some of the "red flags". I am going to try and paste it in below, just in case you can't find the thread:
""Head down on the floor is a sign- but playing with toys properly (ie pushing train along and saying chuff chuff) is totally normal.
OK before I get into things that would worry me I will say that so far you haven't said naything that would particularly get alarm bells ringing but first a bit about diagnoses- At his age you really wouldn't see Aspergers (well it gets confusing and it's all semantics but the pros would be talking ASD unless you were in the States when you'd be PDD) What I'm trying to say is not to say "is he Aspergers/between Aspergers and normal/high functioning autism/ etc etc" because at 3 you would have no way of knowing. All you can do really is say "are there enough signs here to worry me?" (we're all abit on the continuum and all children will have some signs if you're looking at a checklist).
Ignore affection- it's irrlevent! There are autistic children who are very defensive about being touched, but every autistic child I happen to know is very affectionate. DS1 is far cuddlier than his peers and than his NT brother. So forget that entirely.
OK onto things that would ring warning bells. As a baby either very hard to please, always crying or extremely placcid. My ds1 was the easiest baby in the world. He was happy to spend a long time looking at ceilings! Very smiley, very sociable, very placcid.
Not playing appropriately. Rather than playing with a train, just looking at the wheels. As a baby maybe moving things from one pile to another. Lining things up (although ds 1 have never done this- much to the consternation of the clinical psych- and his most NT friend did it all the time). Maybe turning a ball over and over.
Manic laughter (!!) They all seem to do this! At 4 months ds1 heard his first pigeons and just killed himself laughing- really creased up like it was the most hilarious things in the world. DS2 has never laughed like that. He laughs but it doesn't have the manic edge! At 18 months DS1 would read books really intently and then turn then upside down and kill himself laughing all the way through (becuase they were upside down).
Being "moved" by music (especially classical). When the olympics were on the theme tune would make ds1 shake. He would stop and go rigid when he heard it.
Being obsessive about things like lights. Maybe they always have to be on, maybe flicked on and off. Obsessions about traffic lights. Absolute fear or absolute obsession with the hoover. DS1 used to pounce on the hoover and glue himself to it. He's now terrified of it and cries if I turn it on. But obsessed with them. if we see one in a shop or on tv or in a mag all we get is "mmdan mmdan" (hoover hoover).
The big big big one is pointing. Most NT childen develop pointing at around 12 months. And the important one is protodeclarative pointing- pointing out things of interest (as you mention above). DS1 does that- but not as often as ds2, and he's a bit vague about the direction he's poinitng in. It also developed later. (Although he had shared attention from a young age) Rather than point at something in a book. or something he wants he'll tend to take my hand and place it on the object (that's what the checklists mean by "using adult hand as a tool"
I think eye contact (especially with familiar people) is a bit misleading. Ds1's eye contact when he is relaxed is excellent, but when he's stressed non-existent. It's generally pretty good with adults, but if a child approaches him and he isn't sure what they want him to do he will totally blank them. It's incredible- like he hasn't seen them.
Finding copying difficult. You may have to actually teach things like drinking form a cup, using a spoon (I did- at 18 months). Couldn't believe it when ds2 just drank out of a beaker at 4 months. Still get a feeling of amazement when he does it now at 14 moths.
DS1 isn't bothered by change, isn't particularly fussed by routine. Hates shoes, haircuts etc. IME an autistic tantrum is something different form a usual toddler tantrum as it has a real "fear" behind it (not to say they don't have normal tantrums as well). But the intensity of one which has been kicked off by the autism- rather than just a stop is something else.
Imaginative play. If your son can pretend that a stick is something else, say a gun or a spaceship- then you have absolutely nothing to worry about. My son can't do that although he will play imaginatively with things like his teletubbies play set or dolls houses. I bought him a dolls office set the other day (computer etc) for his fort. He liked the swivel chair, but he twisted it and examined it upside down rather than pretending a soldier was sitting in it or something.
Other oddd things. Looking at things out of the corner of their eyes (that's a classic). Flicking things in front of their eyes (ds1 doesn't really do that but lots do) He does run a train station by the side of his head though.
DS1 likes other children, and likes being around them but will ignore them. If you say "A give so and so a kiss" he will do, but tends to keep away as much as possible. Like seeing friends though and would be really upset if I said we were going to see someone who was then out.
Um that's all I can think of really. Hope it's put your mind at rest! Things like an insistence on rouine would tend to go with an anxious child- not necessarily an autistic one (autism makes the child anxious which then leads to the routines- but you could just have the anxiety without the autism iyswim),
If youa re worried- have a chat to your HV. As he may have a language problem it may be worth getting a referral to SALT. Your nursery may be able to refer, your HV certainly can. I only say that as the waiting lists are so so so long- and you can always cancel if you don't need the appointment.
It may be worth trying to get hold of some stuff on the Hanen programme- it's good stuff and makes a difference. It was developed for childen with language/communication delay. I can't remember the name of their parent book, but I can find out. I think it's sold through Amazon. Hanen techniques really helped/help us, and their great for all degrees of problem.
Once again though I haven't really read anything in your message that would particularly set off alarm bells. Feel free to ask anymore questions. I've tried to give examples of things I know other autistic chidlren do, but I'll have missed out loads."
In answer to your specific question, yes I was worried about my DS1 by the time he was a year old.
What are you worried about with your DD? I know you have posted about her high-pitched/squealy cry before - what else?