If I was you I would go to your GP again, and push for a referral to a developmental paed. It is not the case that at 2.3 he is too young to be assessed - and given that there will inevitably be a long waiting list he's likely to be nearer 3 by the time an appt comes along.
If he turns out to be fine and your worries unfounded, you haven't lost anything. But if you are still concerned you can be reassured that you haven't wasted any time. Early intervention is so important with ASD (if it is that, not saying it is of course - and many of the problems you've listed could easily be down to speech delay rather than ASD).
In the meantime, to help him, I would look at all the areas which you think he struggles with, there are ways to help him.
communication - def look at More than Words. Keep language very very simple. When you want his attention, touch him or make sure he sees you when you call his name or talk to him. Label everything clearly for him (eg "mummy's got some juice" touch the juice). Use third person rather than pronouns if this confuses him (ie mummy, ds name, daddy etc rather than me/you/I). When he responds as you'd like (to anything, request or whatever) give him huge huge praise. Try visual aids (pictures of things) if you think he would understand this better.
play & interaction - get him socialising as much as possible. When you do (at playgroups, playdates etc) don't just leave him to it as other mums do - you'll have to get in there and help out to make sure he's learning how to interact. Start a game going with him and 1 or 2 other children (somehting like bubbles, racing, cars) and make it really really really fun - make sure he's involved. Show him that it is so much fun playing with others (more fun than playing on his own). Great time of year for this, as you can do loads outside with things like water, sand, soil, which all kids love.
He sounds like a sweetheart, and it's a great sign that he seems to be working hard to communicate - if you can help him with this you have helped solve a big part of any problems he might have.
Btw the HV is talking absolute rubbish about no sleep problems = no asd. My ds (HFA) has always been a fantastic sleeper