I had enough trouble trying to raise a kid without the added burden of ASD, and have wondered the same as you, how far to push? While htere is a very natural parental desire to protect I am sure it can be taken too far for the very reasons you gave.
I never was able to come up with a consistent set of 'rules' as the ground kept changing. I and my partner knew as adults we has an understanding of priorities and consequences and often relied -for better or worse - on instinct. An example was if we did not take the child to the dentist for an abscessed broken tooth then trouble would escalate over time .
Trying to get this concept across to a young person was not easy, but due to a very capable and comforting dentist it worked out. It could so easily gone the other way with the degree of distress felt by the young person getting us to call the whole thing off - at least for a while.
I'd not presume to advise you on your situation, but might mention two thing. I apologize if I'm telling you what you have already done or know.
Others will have faced the same experiences, and these can be the basis of support groups. If you have not already done so I'd suggest finding if one exists near you. Our 24/7 Help Line (1300 22 4636) may have a listing for your area or have other suggestions.
The second is to see what is available here on the Forum, not quite as straightforward and it will take time.
Using the Google Search engine type in:
autism beyondblue forum
ASD beyondblue forum
You will get a lot of hits and may well find material that helps as you read though the resultant posts and threads.
I hope this has been of some use