I really want to be brave but I can't idk I am very stuck in this.

Firstly please excuse my english it's very weak. I am a very coward person, idk how much I try that whenever I will have a next conversation with someone I am the less powerful one in that conversation always. For example if a Swiggy delivery boy come then I am even scared to asked him if he has change. My voice is not very deep, and othe other person voices are always deeper than me. This makes sense because I've experienced one have deeper voice amongst my friend are taken more serious. I have deep voice in the morning or normally when I talk but I don't know whenever I have a man to man conversation with someone from outside my family, my voice suddenly gets thin from deep. Ik it's because of nervousness but I can't help it somehow at that time. I always give the command to other person having a conversation. For example a really confident person who's not scared of anyone if he says to a electrician working in a building "arey bhai! Wire baju hata na kya bich me rakha hai" then he will suddenly keep it aside. But when I try to say it the response would be "tho? Udar se jaao / jaa na" - this is an example I hope this convey my feelings Because incident like these has happened many times in front of my mom sis as well it's really embarrassing. I am a grown up 28 year old (i looke yonger 21-22) and people anyone from a iron wala to plumber don't take me seriously while to do to some of my same age people. I ak sorry for the English but I hope I was able to convey my feelings. I feel really bad and coward. And I really try to now becoming coward but I really can't help it