This is more than shy; after all, your son is now 14 years old. I suspect what you are seeing is "social anxiety". I might suggest you google the phrase "social anxiety in teenagers" or "social anxiety disorder" or similar words/phrases to see if the descriptions remind you of your son. You mentioned that your son only talks to one or two friends - is he able to speak to his teachers and other adults? If not, then your son is selectively mute - a behaviour of severe social anxiety. The best information re this issue on the internet is "selectivemutism.org" where reading the FAQ's would be a wise place to start.
You mentioned ADD so I suspect your son is not doing as well as expected in school. This is very common with children suffering from anxiety. Their brains are often consumed with fears/anxieties (albeit perceived) that learning is very difficult for them. Some children with anxiety are also very hyper and overly active even though they are not suffering from ADHD. Anxiety does exhibit so many varied behaviours.
If you feel that your son does suffer from SA, then contact your family doctor re advice. This does not mean that your son would be given medication, just that the doctor should be able to give you a "plan" so that you can help your son. If he/she is unable to help you, then ask for a referral to a medical mental health specialist with experience in anxiety disorders. By the way, if your son is suffering from social anxiety, I assure you that he will not outgrow it nor will it go away; but anxiety is common, highly treatable and usually has an excellent prognosis. All the best ...
Just shy, I had one child like that doesnt mean they have ADD does he do sports or after school activities, perhaps he would like to join something, another thought ask a child of a similar age round to your house, you say he has one or two friends maybe he talks more when you are'nt around some kids are like that shy in front of parents ...