I would like to put in a cautionary word: People at the age of fifteen do not often just start stuttering for no reason. The first line of diagnosis is to get a very good, very thorough physical with this concern presented as a focal point. Stuttering is often considered a neurologically-based behavioral pattern. I wouldn't want you to miss something that is physical (or neurological). When and if this turns out to be a non-contributing factor, seeing a psychiatrist (if you are concerned about your emotions) would be a second focal point. If it is then determined that your emotions are not the cause, a speech-language pathologist could evaluate your stuttering. None of this is meant to worry you. If it were me, or my child, I would think along these lines. These are my thoughts only. I like to think logically. Bright individuals, such as yourself, can sift through this information and take from it what they think is best. In the meantime, please be good to yourself.