I had a professor who stuttered and for the most part overcame his stutter. He gave me great advice which was "We only grow when we push our comfort zone." This is true for all of life, not just stuttering. I say do the presentations. The more you do, push your comfort zone, the easier they will get. Life is going to be about choosing to muster courage over giving into fear. Now I often seek out these challenging situations and my anxiety has more the most part gone away.