When I had my scans for my twins, they both looked absolutely fine. Screening revealed nothing problematic. Then one of my twins stopped growing, stopped moving and nearly died. He has a very rare illness (one in 80k) which requires a lot of monitoring and care.
There are a few conditions that are screened for, because they can, but in reality any child can be born with any one of thousands of disabilities and you would never know it in advance. I met a woman in hospital the other day whose twins have cerebral palsy and epilepsy, and need far more care than my niece who has DS.
I’m just trying to say that having a baby carries a risk of having a baby with a disability or health problem, and this takes some getting used to - in some ways knowing in advance is a positive thing, it gives you time to process and research and figure things out.
There should be a genetic counsellor available for you to talk to, and I’m sure there are support groups in your area or online.
My son with his scary rare illness is just my son, just like my other son, I don’t think of him differently, I just have to pay a bit more attention to him. Hang in there 