I have a 2 year old that was diagnosed with ASD this April, so it's pretty fresh. I worried about him a ton from early on- when he wasn't meeting the milestones at Drs appointments, when he struggled to speak or eat more than the other kiddos his age I knew, etc. Getting the diagnosis and the uncertainty while waiting was probably the worst part for me. But really once we got the diagnosis, I was able to go into mama bear "make it better" mode where I focused my worry energy on getting him set up in therapy services, researching ABA, and working with him where he is at to make his own goals I set for him instead of the traditional paced ones the doctor sets.
I certainly do still have sad or worried moments. I wonder about his future and I worry about who will care for him when I'm gone since he doesn't have siblings. I worry that someday his peers may make fun of him or he may have a hard time making it in this very ablest-focused world. I even throw pity parties for myself at times where I mourn not being able to go do "normal" things like eat at restaurants with him or take him on big outings like hikes or theme parks. But ultimately when I really look at him for who he is, I am amazed by how incredibly special he is and how lucky I am to be his mama. His victories feel so much bigger because we work so much harder for them. He is mostly nonverbal so the things he does say are so strikingly sweet (mama, thank you, please, love you). His joy is so palpable in our good moments and his love for me is tangible during his hurts.
For anybody else entering into this I'd give this advice: Allow yourself to worry and grieve for a moment, but then really make yourself look at what is in front of you. Neurodivergent kiddos can be so incredible and have so much to teach the world.