It is so hard, but natural to spend the first few years comparing DC against the milestones and peers.
And you're right to be concerned, even if there's nothing to worry about - it's good to be aware of his development and care about how to support him best.
It sounds like you're specifically concerned about ASD - in general ASD diagnoses before the age of 2-yo aren't considered reliable, as there is just so much learning and developing that happens between the ages of 1 and 2. And there's a big developmental leap between 14 months and 24 months.
If it's any reassurance, DD didn't walk at 14 months, or at 15, 16, or 17 months - at 18 months the HV suggested we put her on the 'list' which is a list of children who were showing developmental delays - at 18 months a 6 days she walked (tip toes, a red flag in my mind). At nearly 4-yo she is still behind her peers in her gross motor skills (though swears blind she's the fastest runner in her nursery class).
All that time she was refusing to walk (or stand, or bear weight in any way - I mean, she didn't even sit up un-aided until 8 months), she learned to talk before her peers, and has excellent fine motor skills.
They all develop at different rates, and it often seems that if a child has spent their brain energy learning physical skills their fine motor and communication skills fall by the wayside, and vice versa.
I echo what @Disappointedkoala said about a hearing test (these can sometimes be done at the optician if the doctor isn't seeing people face-to-face).
DD still does things that the internet says are 'red flags' (the tip toeing, she's texture adverse to the point of gagging) - but when I look at her as a whole child, rather than as the milestones I'd expect, I'm quite sure that she's NT, she's just good at some stuff, and not so good at other stuff. And at some point she'll probably catch-up (or not, I'm 40 and I'm still a shitty runner).