I can’t remember how many times I have heard people say:
“I don’t feel confident in my English.”
“I feel nervous when I speak English.”
“I lose my confidence when I speak English.”
Confidence has very little to do with your English skills.
I’ve had many students with very poor English skills but high self-confidence who were still able to get their message across and I’ve also had students with high-intermediate English skills but low self-confidence who were struggling to share their opinion
Longman dictionary defines confidence as the belief that you have the ability to do things well -- here is your answer — become a confident speaker of English by learning to speak English well
But most importantly, you have things to say, things of value to other people. English alone won't get you far, English is an extremely important tool, but it is a just tool, you need that tool to help you display your real skills and expertise.