Hello. Sir based on the history you have given I think you should know that there are many reasons which causes stammering like a strong family history, psychological reasons like anxiety, stress, family enviroment. Generally stammering is treated with the help of speech therapy but you should know that it takes longer duration for a better possible outcome and the result of speech therapy will not stop your problem overnight, it takes time to resolve your issue through that. So I kindly advise you to consult a speech therapist for further queries.