I'm not 100% sure, as we have a Psychologist (there is only one in the clinic and he cannot take all our referrals, I don't think he does an ADOS), whom send the referrals for testing or we ask the parents to send their kids to the school district to do the testing (via an IEP), our job as the Psychiatrists is just do the medication management. I will check with the Pscyhologist to see if he uses any validated assessment tools. However, as far as diagnosing Autism, we have just been instructed to stick to DSM 5 criteria and ask good questions about history. But it is still quite difficult to assess.
Keep in mind that this is a county run clinic where our resources are limited.
It sounds like you are in a really unfortunate situation and you are not getting the training that you need. This is not a position you should be in, and htat is not enough time to make a diagnosis particularly for older kids or those without really clearcut symptoms.
The ADI-R can take about 2 hours to administer (time varies significantly depending on age of the kid) but still should be used in conjunction with other rating scales (We use CARS, SCQ, & SRS most frequently) -- and DEFINITELY including other means to suss out other psych concerns. ADHD , anxiety, and mood disorders are super common in ASD-- but also on their own can cause symptoms that look like ASD, espeically with regard to the social communication items (but also perseverative thinking). That's why we typically include CBCL, Conners and/or BRIEF and sometimes anxiety and/or depression measures. And kids who have global developmental delay / ID more often have stereotyped behaiors and some of the other symptoms of ASD; you have to make sure you are considering their overall cognitive level when you are assessing their behaviors.
So in short it sounds like you're in a near impossible position for cases that aren't basically a waiting room diagnosis. We don't do 2nd opinions in my clinic but we do a lot of 3rd opinions- often because someone has rec'd a dx through their pediatrician or similar, then family asked for school assessment to get IEP under ASD category, and the school did a more thorough assessment and said no. (To be fair, it is sometimes the other way around but that is the more common scenario, and the school districts immediately surrounding me are quite good at this thankfully).
You should be aware that there is a very important difference between a SCHOOL diagnosis (from the school system, often but not always by masters-level rather than doctoral clinicians). MOST insurance companies DO NOT ACCEPT school diagnoses. If the family wants to get behavioral health services for ASD through insurance, generally they need to get a MEDICAL diagnosis (doctoral level psychologist, MD, etc).
The best way I can see for you to muddle through given your seeming constraints is that unless it's a very clear diagnosis, to learn how to do a jam-up interview getting lots of good examples of past and current behavior and deliver the appropriate measures as much as you have time for (including to screen for comorbidities). Have parents come like Then you could give a provisional diagnosis if it seems appropriate, refer them to get additional testing (through the school perhaps) and then send you the full report to include developmental / cognitive testing and ADOS as a step 2 follow up. Still not a good situation. The fact that y'all don't have standard parent-report measures readily available is a bad sign if you're actually giving diagnoses. I hear you that your clinic is under-resourced but many of these are pretty inexpensive. (And some screeners are free, like the MCHAT, althouh those are just screeners and not diagnostic tools per se).
Your situation sounds alarming though maybe not all that uncommon sadly. Send me a PM if you're interested and I'll share a doc of a guided interview with some examples we use with students in our clinic, which would be better than nothing if you can't do / get an ADI-R.