Autistic? Slow development? Stubborn? Normal? Or worrying?

Hi mummies, my son was born in oct he is currently 26 months old..he is able to say alphabets(even what each alphabet stands for), numbers(1-20), colours(common ones) and random 1 words..he is still developing his speaking(he has slight tongue tie-had a day surgery confirm but back out when he started reading alphabets aloud)..he is quite active..appetite is also good..motor skills are as expected..

but what worries me is his reluctance to look at people when called out..he looks and smiles and any other normal kid but only when he wants to..he tends to daze..needs to organise toys as how he wants or he will get annoyed for a short while, nothing major..runs along the same path as if he is deep in thoughts..randomly laughs(which I reckon could be normal..) a little stubborn(like to let loose of his body when it doesn’t go his way esp when we are walking..and he wants to do or go somewhere different)..and lastly he doesn’t like to interact wid other kids..or people..

This is my 2nd child..the 1st was very well behaved and loved the company of people although he too started speaking late(I was told then that boys can speak as late as 4 years old)..but I have always thought this 2nd one has always been difficult since birth..He was born a month early..abt a week or 2 premature..but he had achieved his milestones as supposed to..I dunno if I should give him more time? Bcz some kids can be a late bloomer or their personality cld be jz like that? Or I should seek help immediately cz if it’s really autistism then the earlier help is given, the better right? I am gonna book an doctor appt ASAP regardless, as my instinct seems to be getting stronger...but I hope u guys can share if you have had similiar experiences