NikandE, many wise words from others here already. Take it easy, get used to the info you already have. There's plenty of time.
Treatments can be great, but what really helps all the time is knowing how we think, how our way of seeing and experiencing the world is very different from others around us. Your daughter is likely to be able to hear things you can't, see things in a different way to you, experience smell, taste and texture in ways that are different from yours. It's difficult to explain why we fixate on things, how patterns and numbers and facts are far more interesting than people and their relationships with each other, but that's because our brains are genuinely differently wired up.
Most people are born with brains that are wired up to work out what other people think and feel. Ours aren't. They're wired in for numbers, facts, patterns, logic, social responsibility, loyalty. We have to learn every bit of human social behaviour from books and films and painstaking research over many years, and it will always be an exhausting foreign language to us, no matter how good we get at speaking it.
I can only speak from my own experience: What would have really, really helped me as a child was the knowledge that I personally didn't benefit at all from eye contact, nor from social events that my parents chose for me. Those were things that my parents benefited from making me do, so they could feel they had a 'normal' child. To me, the way I am is normal. This is how I am. The rest of the world is not-normal to those on the autistic spectrum. We understand each other just fine. We parallel-play because that's what works for us. It's not a broken or damaged or disabled way of playing, it's just different and it respects our needs. We need to learn not to be rude to other people, certainly, and to put up with a certain amount of social behaviour in order to make friends. But my friends are people who cope with me as I am, not people who want me to be something I'm not, if that makes sense?
We're great at individual things where we can practice it over and over again, and very often we'll go on to be better than anyone else at those specialised things. Not everyone will, but many of us do.
I needed to socialise on my own terms, in my own way, not be forced to be something I wasn't. I worry about a few (not all) of the training programs for ASDs because a few are so focused on getting the child to be something they're not, perhaps so that others can feel better about them and relate to them better. That can be a totally stressful and exhausting thing for the child. Yes, we have to learn to fit in somehow, because society certainly can't do all the adapting, but I'd say be wary of any program that doesn't allow space for your daughter to be who she is, or treats an ASD as some horrific thing and something to be entirely programmed out of the child. Look for what she's good at, and build on those strengths if you can. Be there for her when no-one else is. Value her for who she is. She has a great parent, and that's what counts.