I had the same! and the same kind of blockage later on when I became 18. I visited a speech therapist with a different view, and she deliberatly let me stutter against strangers to give me the feeling that I did have control over my speech. It did help in the sense that I do not care about the stuttering, and while it is not faultless, it is a lot more relieving than trying to push my words out. What also gives a tremendous change, is the fact how much I am rested and stress free. When I'm completely worry free, it's like I do not have a stutter problem at all. But the key is in a tl;dr: Not to care. You do have the block, don't get frusty over it, that only aggrevates the case. You could try the same as I had, deliberately stutter to people to gain a sense of control (it takes balls to do so!). When I moved away, that speech therapist did warn me about other therapist who do focus on "symptom relief", which only helps in the shortterm with tricks that do not uphold for months on end. This is a very american way of dealing with it, so it may be harder in your environment to avoid this.