I used to be the same way, too (still am on occasion, but you can't always get rid of a passive personality). I'd talk and people'd talk over me, and I couldn't but into a conversation or a situation, even if I absolutely NEEDED to.
Posted by Nicole
I've noticed in my case a lot of it seems to be from my tone of voice; I tend to speak very quietly in such a way that is easily ignored, so maybe a way to get more attention would be to try and speak louder?
I find this worked for me. I talk much more assertively and louder now, and actually, I blame that tone of voice on Let's Playing. I basically PRACTICED louder and... I'd say "alive" speaking to myself, for the internet. It actually helped quite a bit, you'd be surprise. I'm not saying you need to sit in your room and practice into the mic speaking, that sounds silly, but speaking a little more assertively will help. Of course, not TOO assertive now, but that goes without saying.
"GIVE ME SOME FUCKING SERVICE" will not get you far.