What does you and your child's ADHD/autism journey look like?

I have a young son with suspected ADHD, possible autism, anxiety. I was only made aware (by educators) that he was showing traits last year in preschool. He's my first child and I assumed his behaviours were normal for his age. I felt like I was proactive from the start (implementing strategies at school and home, diet, consulting with a paediatrian, trialing a medication that didn't work- just made him fall asleep) but it's been over a year now and his inability to focus during kindy has been detrimental. I booked him to see the Paediatrician again but it took months and months to get in. The paediatrian has referred him for speech therapy, phycology assessment, vision and hearing tests, EEG tests and blood tests. I'm feeling overwhelmed. I will be doing all these things but the wait times are so extensive. Will my son be in year 1, 2, 3 before he is able to get the assistance he needs? Also I don't have private health insurance and the cost has been well over $1500 already just for consults. How do you afford it? I will pay whatever it takes but it's going to be a financial struggle.
Am I doing everything I can? How long does the process take? Will he be put on medication after medication until we find the right one? I just feel lost and out of my depth. There must be so many other parents experiencing this, are there groups I can look to for advice?
How did your journey look from start to finish? What advice can you give?
Thankyou