I can completely empathise and sympathise with how you're feeling. I agree with others when they say that the anxiety is the route of your outlook on this situation rather than the fear of being the parent of a child who is disabled. I have a very similar train of thought to the one you have and I know how awful and consuming it is to feel this way.
Please please please do not abort your baby for this reason alone, I don't want to make you feel worse but this sort of action is what would fill you with guilt for the rest of your life, not having a child who has an extremely tiny chance of being less than "perfect" - whatever that means. Even if you were to conceive again in the future and did everything by the book but your child still developed autism, I can assure you that you'd find something that you did in those 9 months and blame yourself.
I found out I was pregnant at 5 weeks and during this time I was taking a very strong dose of antidepressants daily AND if I hadn't been doing this then I would have also been drinking quite heavily as it coincided with the Christmas/NY period. I felt guilty too but I was able to forgive myself and realise that I couldn't blame myself if anything was to go wrong with the pregnancy. I'm now 30+2 weeks pregnant and my baby is developing and growing perfectly. I've not allowed myself to feel guilty since about taking ADs before realising I was pregnant because it really isn't something I had control over and neither did you.
Op the fact that you are worrying so much about this now shows that you would be an amazing, caring mummy and that is the only thing that you should focus on here. I know a million people could say the same thing I've said and it still wouldn't help or change the way you think but if there's anything I've learnt during pregnancy it's that nothing is ever going to be perfect.
Don't write this pregnancy off as something you could have worked better at. The little face looking up at you in 8 months will never know anything other than the fact that YOU are his or her entire world and that really is all that matters here.
Also searching for answers and reassurance on websites is the absolute devil when you feel as low as you do now - I'm going through a lot of anxiety over something at the moment and have been torturing myself by researching the "what ifs?"
I really hope you can feel better about this. Feel free to message me if you want to talk x