Why do i get angry so easily?

i want to know why i get so angry so easy and what can i do to change that, i can get really mad if somebody just tells me something i don't wanna hear like, be quiet or to stop doing something, and i really hate it. i get mad with my parents, siblings, mostly everybody. im only 13, im home schooled and don't go to any kinds of activities so i don't have any friends, we hardly ever go anywhere, if we leave its to got to the store or to get something to eat, we don't go anywhere fun so im always bored, i stay locked in my room mostly all day unless i have to go pee or dinner is done or im thirsty. i used to share with people but know lately when my sisters ask me for something i get mad and i don't know why! it kills me that im like this because i used to be a really sweet girl, this has been going on for about 1 1/2 years. i hate doing school i don't do it that much and i'll get mad if someone tells me why i don't go. i don't have any communication with people unless its to my parents or sibling or brother-in laws, i used to talk to my cousins a lot but they don't talk to me anymore and i don't know why, but there is no one my age to talk to about stuff kids my age talk about and i hate that. plus i don't exorcise and im not really overweight im actually not fat i just don't have a flat stomach and i have some love handles but i have big bones so about 15 pounds of my weight is bones. but being like this angers me also because i hate looking fat my clothes look horrible on me. so if someone could help me with my problems i would just love you! thank you!!