Well at the very least you're willing to take a step back to assess the situation and acknowledge that meds might not be what's right for her, and by extension your family, which is an important first step.

I can understand how overwhelming it can be with all the advise coming from every direction, and also how easy it can be to trust the "professionals", but never forget - they are just people, often trying to make their job as easy as they can, and with biases that inform that (in this case mostly capitalistic ableism - focusing on how we need to "fit in" and be "contributing" or "functioning" members of society when the measure is potential employment and "independence" rather than focusing on our well being and on if our needs are being met), and gaps in knowledge like everyone else (you'd be horrified to know how few health and education professionals get any training or education on working with autistic people).

But all the fights and irritation that can be avoided has so many side effects. And we saw a very different person back when she took them, happy and at least more content

This could be a sign that she is content, it could also be a sign that she is being prevented by the meds from expressing her distress. You not seeing an obvious reason for irritation (that could easily lead to a fight be virtue of simply being overwhelmed) doesn't mean there isn't one, and while not all sources of irritation can be removed from our environment, removing the ability to express the feelings they cause is not the solution.

I just want to make sure I'm clear again - meds can be lifechanging for some people, I am not anti-meds on principle, what I am is cautious about treating symptoms over cause, as well as others' convenience over her well being, because that's unlikely to end well long term.

Lastly, I think if you've not come across them yet, understanding the models of disability would be a good place to start:

https://www.drakemusic.org/blog/nim-ralph/understanding-disability/