It is okay to do what you want and make choices that you feel will help make you happy in life. Moving, changing jobs, and making new friends are normal choices people make, thinking that it is the path to happiness. However, sometimes it is what we consider "selfish" to be the key to happiness.
If there is someone in your life that makes you unhappy, then kick them out of your life. Walk away, block them, stop talking to them, do everything you need to make sure they are no longer in your life. Yes, most people would consider this selfish, tell you to get over it, and just deal with it. No, be happy. Leave the negative people alone.
Buy that cute dress. Eat that second piece of cake. If you are hesitating about making a decision, just do it. Wouldn't you rather regret doing it than regret not doing it? When you finally decide you really should have bought the dress, it will be gone and when you go for that second piece of cake, someone already ate it.
Live for yourself first. Do not be rude or do things intentionally to hurt others. It is okay to talk things over with friends and family and listen to advice, just remember in the end, it is you who needs to be happy. No matter what you do, family will always be family and you can always make new friends. If you like your style of clothing, rock it. You want to travel, then leave! Send postcards. It is okay to put yourself first and make choices that make you happy.
Family is important and so is having friends, but before you can have strong relationships with either, you need to have a great relationship with yourself. You need to be happy and confident and make life choices based on what you want. One day, in the end, the only person you will have is yourself.
If some of the decisions you make turn out for the worst, just use it as a learning experience. Everyone makes mistakes and even though people warn us, we still make them.
Stop letting others tell you how to feel and to "just get over it" every time you try to explain your feelings. Stop explaining, stop trying, and just do what makes you happy. It is okay to upset others, they are not living your life and others will never fully understand your emotions. Wear that low cut top, listen to rock 'n roll, eat the entire cake, and tell that dirty joke. Your happiness matters, so start being happy.