I completely empathise with you. I developed stammering at the age of 15. Two years back I seeked out professional help. But I did not learn the mechanics of improving my speech. Rather, I was asked to step out of my comfort zone. I went out, spoke to strangers. I hesitated and waited for hours before initiating a conversation with any strangers. But all those conversations were insightful. I also taught a few students and believe me explaining something to someone actually helps. The thing is it's more about being more confidence. Put yourself in awkward situations. Don't think that others should like. Like yourself first. Be comfortable with yourself. P.S.: I can say my stammering frequency has decreased by 70%.