Some things about your fears I think you should know.
1. You're always impacting others. Never fear otherwise. 2. What you see as a threat isn't there. It does not exist.
3. What you see/feel in someone else exists in you as well. Feelings of jealousy towards a friend for being a successful speaker shows 2 things being reflected. One, that fear is present in you. Two, that potential is present within you. What you see in them exists in you, both the pain and potential. Smile with gratitude when you're jealous and laugh it all away because as surely as you see that your friend is a great speaker, you realize that the jealousy tells you that same potential exists in you as well.
It's there if you can see past the barking inner dogs called jealousy, anger, doubt, etc. that want you to believe it isn't. But the sheer fact that you feel anger or doubt shows that it is within you. It isn't a question of,
"Do I have what it takes? Do I have it in me?"
The answer is yes, you do. But will you acknowledge it? Will you celebrate it in others as you would yourself? And will you let it move through you so that you can act upon it? It's there. Take a look. Ignore the barking dogs.
4. Everyone feels small sometimes, but this is not what you should fixate on. Be kind to others and yourself in moments of doubt and vulnerability and move through the doubt to a higher energy where the power of your purpose lays. Hyper or hypo-inflating is symptomatic of the same disease. We are all on the same playing field. When you find yourself not believing that and feeling angry or jealous, see #3. Remind yourself of who you are.