Hi- I am a mum and a Speech and Language Therapist. I would definitely recommend getting some advice. You can see your GP or health visitor who can refer your son to your local service. I dont know which your local service would be or what age they accept children- its 2.5 in some areas but any age in others. If you want to go private, you can look at
http://www.helpwithtalking.com which lists registered SLTs in your area and you can search by age etc. Your Speech and Language Therapist will be able to talk to you about whether there is a problem and how to help him. They will take a history which will include whether he has had a hearing test and the results as this is so important to learning to talk. When you are thinking about getting advice, I'd say the earlier the better as there are so many ways to help children's communication. Makaton, as previously mentioned by other posters, is really useful as it's always used alongside spoken language and another tool to help children communicate. It's just as important for you as for your son to get some advice as you are obviously worried and you don't want it to get in the way of having fun with your 2 year old!