My experience is a bit different, as my DS had a severe receptive and expressive language delay at 3, but had a language spurt between 4.5 and 5, and is mostly doing well, but is somewhat quirky/bordering on food phobic, socially immature. (he only got a DX of language delay and subtle social communication dificulties, not a full autism DX). The pre-school years were utterly grim tho.
I think the difficulty with counselling tho is finding someone specialised enough - with either direct experience of SN or enough empathy to not just spout the usual platitudes you hear everywhere else - einstein, they all get there in the end, he just needs to go to nursery, school etc. Agree that the pre-school years are a nightmare - you don't know what the outcome will be, you feel so isolated (irony is there will be other SN parents locally feeling equally isolated but somehow you never get to find them at toddler groups etc), and the system grinds ever so slowly.
In terms of do the best for him and keeping hopeful:-
1)professionals will recommend toddler groups as some sort of cure-all. This is somewhat naive. If you can find one activity that isn't gruelling, then give it a go. But otherwise if they are making you miserable, don't force yourself. The park/zoo/soft play/museum/aquarium, etc will be just as educational for him (if that's what enjoys!).
2)expect to have to do your own digging about what support groups/services etc are available locally. eg. if one of your local children's centres does a useful class or courses, don't expect your HV to actually know this. also applies to specialist state nurseries, sadly
3)double check all referrals have been received within a fortnight, if you haven't had an acknowledgement letter.
4)read around yourself, including ASD books, and pick out what works. Don't feel you are somehow betraying your child or being too pessimistic if you get info from ASD books, many strategies that work with kids with SN are suitable for all kids.
5)rightly or wrongly, I found MN SN board an absolutely lifeline and fabulous resource.
6)is portage (sn play worker) available in your area
7)you might want to think about benefits (DLA) etc, if he needs more care than a typical child his age.