Differential diagnostic between autism and cptsd?

I don't know if I have cptsd and autism, or just cptsd. How can I tell if I am autistic too or if all of my symptoms and developmental delays are the result of early, pervasive and sustained childhood trauma? Are there indicators of autism that cannot result from cptsd alone?

I have a lot of the standard symptoms of autism but I know ptsd can mimic other conditions and Occam's razor says one disorder is much more likely than two.

Autistic things I do: deep narrow interests, difficulty paying attention, meltdown from sensory overload, stim, line up/stack toys, difficulty understanding social situations