I know you didn’t ask for advice, but you describe me exactly how my sister would describe me - except I don’t have an ASD diagnosis.
I put myself first and just expect others to do the same. If I asked my sister for a lift and she said yes but only if you do X, Y, Z to make my life easier I’d happily do it. I’d never think of those things without proactively sitting down to think about “what can I do to make this easier for someone else”.
I would also never offer anyone help, but would jump if anyone asked. Mostly because I’d find an offer of help imposing, or a judgement on my abilities because I will ask for help when I need it.
In the same vein, I don’t expect anyone else in the world to put me first as that’s my job, and so I have no problem saying no to things that don’t work for me or communicating my needs. I often find myself saying to people “if you don’t put yourself first, then who will?”.
So despite you not asking for advice, as someone who recognised themselves in this situation, I’d suggest you’re just clearer with your sibling on boundaries and speak up when you need compromise from them - don’t expect them to offer it, they’re not in your brain, they don’t know what you need or what you’re thinking!