Though well intentioned, that's not really the right advice for someone on the autism disorder spectrum. It's kind of like telling a person with muscular dystrophy to try jogging.
Some people with autism do make significant progress to the point where they can achieve a lot and live a fulfilling life. The muscular dystrophy simile is inaccurate and quite disempowering, like saying "sorry your stuck in a condition so don't try to do anything". Getting a formal diagnosis and professional medical advice is of course a good idea as per the other comment. There are stories and research showing the brain can develop and learn in autistic children and they become more able to deal with the social challenges of life [1]. The OP has already said s/he has made progress with shyness, this is an encouragement to take steps forward in other areas too.
[1] http://www.dailymail.co.uk/health/article-2271608/Can-really...