'High-functioning' autism isn't a mental health problem, but it often comes with them - anxiety, depression, OCD, etc. So many people, even so-called professionals, get it wrong about autism. Autism is a pervasive developmental condition - not a disorder, just a difference in seeing the world, so in that sense, yes, it's cognitive. I have female-type Asperger's syndrome - whose traits are more subtle than classic AS - the type mainly found in males, which means that we are often misdiagnosed or not diagnosed at all, which is so wrong! Just because autism isn't a learning disability doesn't mean that life is easy - far from it - yet the professionals tend to downplay our autism for it's not 'obvious'. I simply couldn't manage in certain areas of life without quite intensive support - which I get from a friend (without this, the system would have driven me to suicide). Sometimes learning disabilities come with the autism - such as dyspraxia, dyslexia, dyscalculia, executive dysfunction, etc. It's these, along with the way people treat us that make our lives difficult - not the autism itself. We're constantly being misunderstood. I find that people who suspect they're on the autism spectrum usually are.
Why do you feel you need a diagnosis? I needed one to confirm what I suspected all along, and was told I'd get support - which didn't happen. If you need a diagnosis to get support, and if you suspect you have the female presentation, you really must find someone with experience in that area otherwise you risk being misdiagnosed. Hope this helps