Am i an introvert?

So i should start of saying that i have had very few friends in my life. All my school days went silent without me talking to anyone or they talking to me. I did try to talk to people but they never really wanted to talk much to me. I tried really hard to make friends but since i did not "look like one of them", the friendships were very brief. Now when i am lonely in class and some one asks me something or if i want to eat lunch with them. I always say "no", and feel angry and bad for them because they asked someone like me to eat with them and angry because i think they are pitying me. So now i like to see how many days go by without me saying a word or talking to anyone in school. When someone say if i want to go somewhere i say have something important to do, so i cant. While in realty i don't have anything to do, other then sit and stare at wall thinking about nothing. I don't interact with people at all you could say. So you think i am an introvert? and is it normal to do this?