Yeah I know the feeling. With a lack of communication, families can be frustrating that way. I wouldn't say that it's normal but it does happen so you're not alone.
I know that this doesn't sound like it'll help your current cause but trust me that it usually does in the end. What you first should do is try to understand them. Your family is currently acting very childish so don't expect them to do anything for you yet. You have to take a stand and be the mature one by trying to be considerate to them first. Try to see why they are so sensitive now and what is going on in their lives that is causing them stress. The reason may not actually be you but they're unfortunately taking it all out on you. That's why for just a moment take some time to observe them. After you've analyzed their situation, try to think of things that you can do to help them out. For instance, if they're having a tough time at work or they're really tired all the time, you can help by washing the dishes, cleaning your room, or (if you're old enough and capable of doing so) cook a meal that day. Just little things like that to show that you care. They may not notice it at first but give it some time. Also you can ask how their day was and listen to their problems. In other words, just be there for them. I know that it's difficult to try to do this when they're not treating you the way you want to be treated but, like I said, be the mature one to extend the helping hand first. You can't always expect others, even if it is your family, to reach out to you first and that's sadly how life works. Also it's far more difficult to change them and force them to understand you than it is for you to try to understand them and hope they return the favor.
Also try to think why they are calling you selfish. I'm not saying that you are, but try to think about what is going on that may make them think this way. Do they think that you're not pulling your weight enough in the family? Do they think that all you ever think about is your own problems and disregard theirs? Whatever the case is, trying to know why they're calling you selfish is a step to understanding them and seeing things from their point of view.
I understand if occasionally you need to rant and vent some anger or talk about your problems, but how are you expressing yourself? If you are throwing fits and being fairly outrageous, then that could be something that you need to work on. Stuff like that may annoy your parents over time which is why they may say that you are selfish. If you need any help, you can ask a school counselor or an adult you trust to help you with that.
Also how often do you ever feel like you are upset? If you are feeling upset all the time, your family may think that you're selfish in the sense that you keep moping around about your problems and you just want to be perpetually sad. I was in this situation earlier this year and I know that if this happens it usually isn't because you want to be sad (I mean, who really does?). So if this is your situation, it helps to talk to a trusted adult or talk about it often to other people outside of your family. That way you have already released some of that upset feeling inside you and won't seem as upset when you're at home.
I would also like to extend my help if you would like that. I probably won't be able to help you very much since I'm not a counselor or therapist or anything like that, but I'd be willing to listen if you ever have any problems. I know that it's important to get all that negative energy out and if you ever need an outlet for some of that, feel free to get in touch with me via Blurtit, tweet me on Twitter @Lia_A_Tan, or reach out to me via MySpace (I know MySpace is totally outdated but eh whatever and it's at https://myspace.com/lia1tan). I may not always get back to you right away but I'll get back to you as soon as I can. Also be sure to mention "selfish" in the beginning of your messages so then I'll remember that it's you and prioritize in getting back you :)
Anyway, I hope this helped!