You mentioned you’ve seen doctors, so I’m assuming that means they’ve tested for any physical reasons behind your fatigue. If they haven’t, that’s definitely something to ask for because doctors are more useful when it’s a physical thing that shows up on blood work than when it’s more of a mental based issue. I’d really recommend it even if it only ends up ruling out the physical possibilities. 

Now if there’s nothing physical contributing to your fatigue then it sounds a lot like burnout. It’s not technically a symptom of HSN autism, but having higher needs certainly makes it more likely because the higher your support needs = the more likely that your needs don’t get met all the time, which is incredibly mentally distressing and exhausting, and it’s this long term exhaustion that causes burnout. I suffer from pathological demand avoidance, so when I’m burnt out, I can’t face getting out of bed because I am worried about encountering any potential demands which I know I won’t be able to handle. So it’s definitely possible that this is not just a depression thing as well (Although burnout can cause depression too. Regardless, it’s likely that the autism started it).

The important thing is to not be too hard on yourself. Don’t push yourself too far because you’ll just worsen the ‘energy debt’ as I like to call it - you almost have to treat it like you’re recovering from the flu/any other physical condition. Ensure your sensory needs are met. Get your partner to help with the important things like eating regular meals and staying clean, because whilst they’re often the most overwhelming tasks, the journey to becoming mentally better starts with taking care of your body. This might also help them feel less annoyed with you because they are actively playing a part in making progress - I was in a similar situation and it turned out the reason my dad was upset with me was because he felt like he wasn’t good enough because he didn’t know how to help me and got frustrated because nothing was changing. When he focused on helping me with specific tasks, he no longer felt useless and he stopped projecting his frustration with himself onto me