I had the same problem with reading tabs when I first started way back when. It didn't make sense to me that the top string of the guitar was the bottom string of the tab. Then a buddy explained to me that basically, a tab is like laying your guitar across your lap and looking down at it. And immediately it made a lot more sense to me. Even now, some twenty plus years later, if I'm asked how to read tabs, that's exactly how I explain it.
I'm sorry to say I can't begin to understand how it must be having the tonal problems that come with your being autistic. Have you considered assigning each note a specific number on the fret board? That's all a tab is, anyway – showing how to play a song by indicating what number fret to play it on.
You hear a song you want to learn. Sit down with your bass, listen to the song, and go through it note by note, finding each on the fret board, and then assign a number to it. For instance, maybe the low E could be 1-0 (1st string, 0 fret, meaning you play it open). G could be 1-3 (1st string, 3rd fret). C would be 2-3 (2nd string, 3rd fret). And on and on.
Just a thought. Best of luck to you. Keep playing.