I got higher rate at 2.5 for moderate ASD (up in night alot) without a diagnosis (but professionals letter attached) for DS3
You do more than you think. DS regressed so actually it was easy to see areas where he had been becoming more independent sliding backwards eg dressing self, washing self, toileting, feeding self - all went backwards or vanished, speech and understanding lost - then lots extra time eg restricted diet, routine issues, sleeping issues (wakeful). Then start on all the therapy (we do 20 hours ABA a week), reading up on ASD, meetings, appointments, not being able to walk from a to b without stopping a million times, making visual symbols, learning signing / PECS etc. All the adjustments you have to make eg not taking him to supermarket, not being able to leave him with granny /friends. Yes you have to supervise but could be playing upstairs and it wouldn't always have to be you - you could delegate.
Cerebra guide is really good.
To give you idea what would be normal for that age - DS1 and DS2 (no SN) both out of nappies at 2.5 and dry at night as well by 2.10. Could ask to go to toilet at 2.5. By 3 just took themselves. Talking in sentences. Could walk to shops / into town. Fed selves. started to dress selves. Could communicate needs - to anyone eg if ill, tired, hungry. Slept 12 hours straight. Ate well. Started making friends at 3 so could play independently. Tantrums rare. Could take anywhere eg came along on errands. We could leave them with relatives to look after (DS3 too much of an escape artist to leave 70 year old granny in charge). From 3.5 they had circle of friends whose parents we got to know and we would take turns having each others kids and nipping to shops etc. Trust me your life is much harder than it would be otherwise. I know what you mean you get lured into the idea that your DS is just younger than they are and lose track of what other children their age are doing. Its only when DS has a birthday that it hits me how different it is - usually I don't want him to have a birthday for that reason that it just feels 'wrong' as he's just not ready to a year older.
You could look up early years foundation stage online that gives checklist of what do at different ages and might show areas where behind.