I will say that as someone who was diagnosed somewhat later in life, I think part of why it wasn't caught sooner for me was that doctors seemed to assume "oh, this would've surely been investigated already", because I was such a complex blob of issues. Certainly the severity of my anxiety and depression made more sense in the context of autism.

I don't know if you've ever done a quiz such as the Autism Quotient test before, but you might be interested in trying it. I like this version here, because it discusses some of the many problems that this and other similar tests have. Many diagnostic processes involve at least one of these silly little quizzes, usually the AQ, which I linked. Both doctors and autistics alike agree on the limited utility of these tests though, especially on their own, so take anything it says with a pinch of salt.