frazer - as well as the research that suggests that raised cortisol levels may increase chances of adhd or similar, there is also plenty of research that suggests cortisol is no problem at all. you are just foucussing on the ones that suggest the worst outcome due to your anxiety.
i just want to make sure that you do understand that the lady you meant who has a daughter with DS, didn't cause the DS by worrying during her pregnancy, not at all. not one iota. not possible.
if it helps, when i was pg with ds1, dh got blown up and given a 20% chance of survival, air evacuation, ended up having brain surgery, etc etc etc. i was under an enormous amount of stress, not just because i didn't know whether dh was going to live, but i also thought i might miscarry due to the stress. (dd1 was 15mos and had to get left with a childminder for a week as we were living overseas and no children under 12 were allowed on the neuro ward - and the hospital was 3 hour drive from the house.)
you need to discuss your anxiety sensibly with your gp - and also discuss your fear that your own axiety has somehow damaged ds1. you need to get this out in the open with professionals, so that you can try and work through it. have you got a counsellor or case worker? how are your meds at the moment? if you feel that you are getting worse, you might want to think about changing your current medication - or asking for a different gp, a second opinion so that you can try and get back on an even keel before you contemplate trying for another baby.
it's still very soon after your mc, and perfectly normal to feel anxious as a result, but maybe you do need to go back to/ find a counsellor to discuss all this stuff to try and find a way through.
oh, i've got three kids now btw. after all the stress of dh whilst being pg with ds1, it's actually dd2 who has a disability. she has cerebral palsy. and i wasn't worried at all during my pg.
adhd, asd, cp, none of them show up on amnio, and none of them are conclusively caused by anything in particular, least of all anxiety. you know that the majority of babies are born healthy. you do know that, when you think about it, so statistically the chances of having a healthy baby are in your favour, but there are no guarantees.
go back to the gp and discuss your anxiety levels. and try to get to a counsellor to discuss ds1 and your fear that your anxiety caused his personality traits.
be kind to yourself. x