The concern you have about what other people are thinking is 100% a creation of your own mind. You are scaring yourself.
You have a choice. You can imagine the audience as critical or as approving along with the hope you will succeed. This is entirely under your control. You cannot read their minds so make a positive choice. Surveys show that, except in extraordinary circumstances, the audience will view you positively. After all, they came to hear you talk or they want your participation in a meeting.
Here are some other tips and guidelines.