Realising that you're different from who you assumed you are is a big deal and it will take you time to figure it all out.
It's valid to have complicated feelings and doubts, and OK to express them.
One of the ironies of this is that being autistic makes it more likely that we doubt our own experience. This quote from the Embrace Autism site sums it up for me:
"We are lateral thinkers. Our superior lateral abilities generate multiple relevant possibilities for any problem. So we hypothesize what we might actually be and come up with many alternatives. Even if autism perfectly describes us, we may still have doubts because some of our behaviors can be attributed to other conditions."