I know exactly how you feel.
You can have a spectacular idea, or express how you are feeling, and no one will respond, or even care to hear what you have to say. You may receive a nod or a verbal response, but you can just tell that what you are saying is not being taken into consideration.
Parents are the worst at this. They act as though they hear what you are saying and care about the words coming out of your mouth or the emotions being expressed, but they simply do not give a care.
I can repeat myself seven times and my parents still will ask me the same question in five minutes. Because the answer that I have to give is not important enough for them to take it in and actually care about what I am saying. This starts a lot of fights, because at one point, I obviously flip out about not being heard and having to repeat myself. For this, shots are fired, and all hell breaks loose.
I know exactly how you feel.
So what happens? You begin to elude your own opinion. You find yourself not following your gut and not taking your own advice because, "if no one else will listen to what I have to say then it really must not be important".
When you are sitting in a room full of people and you can answer a question four or five times before someone will notice and say "wait, what are you saying?" is one of the many scenarios that can make a person feel two inches tall.
Or maybe when you begin to tell a story and everyone that started off listening to you just decides to take their attention elsewhere, while you are still telling the story.
I know exactly how you feel.
Not many people know what it feels like to be trapped in a world where you can legitimately have a full conversation with someone who does not hear a word that you say. It is something that gets really annoying really quickly, and it gets overwhelming and depressing after a while.
When you become numb to the feeling of not being heard has got to be the worst. Because at that point, you realize that even if something is terribly wrong, your opinion just does not matter. When people make decisions regarding even your life, your opinion does not matter.
So why give your opinions anymore if you know you won't be heard?
I know exactly how you feel.