DS was diagnosed around his 9th birthday; referral made at 7.
Similar to what OP describes, also he had a history of speech delay as a toddler. Tends to monologue at people. Makes eye contact with "safe" people (at the appointment when he was diagnosed he was clearly talking to the consultant but focused on me. Will often focus on something like the Lego model that he's talking about rather than the person he's talking to. His speech patterns can be repetitive and he'll latch on to phrases easily and often slightly misapply them, current one is "upper hand" which isn't always a flowing substitute for "advantage". He also tends to overuse names so will start "Mummy" but the use it repeatedly through the conversation. I don't know if it comes from my battles to engage his attention to conversation and I have to repeat his name more than average. He does it to DS2 as well.
Took a long time to play with others rather than alongside. Took a long time to develop genuine friendships. He's well liked and respected though. Can talk at quite an adult level. Aged 6, he had us talking for over an hour about the causes of WW2 and Titler's" strategies. His attention span can be very focused and in depth and good luck if it's not on his agenda...
Hates me and DS2 talking to strangers, to the point of physically recoiling sometimes. Hates things like fancy dress that distort non verbal communication.
Masks at school (and previously nursery) but then becomes exhausted. Needs a buffer between school and extra curriculars.
"Tantrummed" for years for all kinds of non-obvious reasons that have made much more sense with hindsight. Had a meltdown over brushing his teeth and missed half his brother's birthday party because it lasted over an hour. His pb is 4 hours because I asked him to change a reading book (one of my final straws leading to referral). Cafés on holiday are a trigger point as they can cause sensory overwhelm, and not knowing exactly what the food will be like. Favours predictable chains.
Generally anxious and perfectionist (perfectionist confirmed in QB test)
Can empathise in odd ways... I let him watch Hot Fuzz thinking the violence was slapstick enough. He loved all the shoot 'em up scenes (and told me about the gun models courtesy of Smithsonian Channel) but sobbed when Nick Angel smashed the lily on the trolley boy's head "He loved that plant!" (He was reassured that it could be safely repotted with no lasting harm 
) and he equated that love with his love for his favourite cuddly, but if he's having a dispute with his brother over their cuddlies, his feelings will override his brother's and he can't feel his brother's worry over his anger. He also struggles with appologies as he usually feels justified in what he did , and he's rubbish at a token one to make people feel better. He can occasionally muster sarcasm, and he's probably made about 5 genuine appologies in his life. It's generally not worth the social mess of trying to push a social niceity appology.
Fantastic child...usually Tends to present fairly normally, but when I did a mindmap of all his social/ sensory and random quirks, the page filled up rapidly and dots started joining up.