Misunderstanding quiet people

Everyone always complains about that one obnoxiously loud person where they are...how they're so rude to talk so loud and all. But do they know that being the opposite of loud and obnoxious is even worse? This is how I feel being the opposite. I am a soft spoken woman. I always have been, ever since I started talking. I don't really notice it nor do I care, because the people who WANT to hear me and who want to hear me do. But the people who I served as a cashier, a sandwich artist at subway, and people I worked with in all places hated it. Some would be rude to me, and others would go as far as to say I'm fired if I don't stop being so quiet, or I NEED to speak up because who knows what I'm saying? Ugh. It really gets to me sometimes. I physically can't "speak up", and find it extremely offensive when people tell me I HAVE to. I'm just a soft spoken person. Who knows, maybe its a medical thing...maybe because I had the cord wrapped around my neck at birth I've got something up with my vocal cords that never was noticed. Who knows what it is? I know for a fact it's not me being "shy". No way in heck could it be that...because I LOVE people and I love talking to tons of people! I will put myself right out there, I will sing in front of huge crowds and speak in front of them...so no, I am not shy. People always tell me they "gotta get me to be loud/speak up/yell/a megaphone/come out of my shell". It's quite annoying when I just can't. They don't understand that it's impossible for me! And I wish they did. I wish everyone who criticized me knew how it felt to be like me. I wish the people who refused to go through my lines regularly when I was a cashier just because I wouldn't yell at them would feel how I feel, just once. This is a quiet cry for an understanding, something I just wish I could get people to do for me. It will never happen but one can hope, right?