@ArraDreaming Not sleeping is the worst.  I'm right in the middle of that myself right now.

I have a massive history of not sleeping.  It's a very common issue with people with autism.  And I have tried all the things, watched all the YouTubes, read all the books, done everything there is to do.  @Former-Member has made some great suggestions.  I might just add something to it.

Declutter the bedroom.  Use the bedroom only for sleep (and the other obvious thing).  Don't watch TV in bed.  Don't use your laptop in bed, or work in bed, or use the bedroom as some kind of multi-purpose room.  The bedroom is for sleep.  Train your mind to understand that once you go to bed, it's sleep time.

This doesn't always work.  As someone with ASD, I was put on melatonin, as that hormone is often lacking with many people.  Personally it didn't work for me either, but I understand it does help many.

If you do go to the doctor, just be very careful what they might prescribe.  My own experience is that doctors tend to be prescription happy.  What I was given was very strong and I had a bad reaction to it, and I understand it can also be very addictive.  I was on another form of medication for 18 months which worked really well for sleep.  I loved that side of it.  But it also worked as a powerful appetite enhancer and I am currently in the process of loosing the extra weight that I gained whilst taking it.  It's also extremely hard to get off of and took weeks of hard yards to get free of it.

Always go natural if you can.  There's some great sleep tracks on YouTube.  And find a good meditation app, that's helps me a lot too.