See this way of thinking has actually landed me in a pretty bad place with my mental health.

"I'm in charge of my own emotions" is not something an autistic person with rigid lines of thinking should internalise, but I did.

As a result I never gave myself permission to feel negative emotions, because who wants to feel negative about anything if they don't have to?

It seemed so smart and healthy, just be happy, that's what everyone always says about the easy fix to mental health. It was easy too, regardless what was happening around me, if I pictured myself feeling happy, I'd feel happy.

I'm in my 30s and regularly mistake sensations with other sensations (am I tired or do I need to pee? They both cause a headache) and also I think all my negative emotions are skipping my brain entirely and coming out my arse in the form of IBS.

I can't picture myself feeling sad to experience sad because I .....don't remember what sad feels like.

I remember what vomiting feels like, because that's how my body has reacted to "sad" recently.

While this is true, I would also add that it's ok and valid to be sad and unhappy. There is no obligation to put on a smile. You can be happy and not smiling, or you can be unhappy and not smiling, just be you.

I feel like it's not my right to be happy unless I can impress in some way, like through work or academia. Everyone else has surpassed me and I can't impress anywhere, so I just feel like I don't deserve happiness anymore.

This is surprisingly uplifting, thank you for posting this

But I would suggest start looking in weird places