Expectations?

Sometimes I wonder if it is my expectations that are too high or I simply expects too much from others. Or probably I am so selfish and self centered that I expect others to think the way I do. Probably I also expect others to know what I mean and to understand me without looking at myself first to see if I convey the message with the right tone, right words, right facial expressions and/or the right body language.
I feel that I am often misunderstood even by my own family on how I say the things I wanted to say. Often I did not meant the way I sounded. My intentions when I said those things were not how others thought it meant when they heard it. Sometimes I may sound demanding but I did not intent to demand for it. I just wanted the other party to know what I wanted but I did not intent to demand to have it right there and then. I am fine to discuss and work out on both of our needs but to the other party I sounded like I am giving an instruction and demand to have it NOW!!
It is very frustrating to be often misunderstood and when you try to explain yourself it make things worse because the other party will think that you are defending yourself and putting them on the blame and this will often lead to heated arguments, shouting, unhappiness and/or not talking to each other for a period of time. I feel that this situation has happened numerous times.
I do not think that I am a bad person nor do I do things on purpose to hurt others that I care for. I maybe selfish at times but I do try to do things to make people I care about happy and also to repay their kindness in one way or another. It may not be in a big way but I really do try. But sometimes before I get to do what I planned to do, another misunderstanding/argument happens which makes me feel that it is not worth my effort trying to do my part because I will always be misunderstood. Probably that person don't even care about me in the first place.
No one really understands me. Not even my Mimi. But often she forgives and forgets easily and faster compare to others instead of really understanding the issue. A few times when I tried to explain myself more, the arguments become worse. Hence sometimes I wonder if it is even worth the effort to explain or just let them view me however they like. But I do not like to be misunderstood. I especially do not like others to say things that I feel it is untrue or injustice to me. Therefore, I have the tendency to defend myself and hence the arguments exploded.
Its probably time for me to start thinking of the whole situation and instead of EXPECTING others to understand me, I should change my expectations on my family, boyfriend and friends. It would probably make me a happier person too....
Why do I expect my Mimi to see my point or be on my side when I argue with my brother and sisters?? Why do I expect my brother to respect me?? Why do I expect my sisters to think I am not as demanding and we can actually discuss on the differences instead of arguing about it?? Why do I expect my boyfriend to put me as first priority in his life?? Why do I expect my good and close friends to be thoughtful and care for me and my feelings?? Why do I expect everyone not to lie to me??

Are all these even possible??

If no, then its really time to wake up and change my expectations.... and also to change myself....
I should start polishing up on my PR skills, communication skills, do not be too calculative, do not expect anything, and just do my part. Then, probably I will be able to portray how I want others to see me and perhaps they would understand me better?? I know it's easier said than done because I already have these expectations in me for 26 years.

The question now is: How do I change all of a sudden??