What?

Hello there :)
Sometimes people said that i'm a quite person well yeah it depends on my mood sometimes i like to talk and other times i don't.Is it possibly that im an anti-social person ? I just don't understand why I am the way I am. I have lots of friends and lots of people that want to hang out with me but I avoid most social situations! I instead spend my time home alone.The strange thing is that I wasn't always like this! Not when I was younger like in elementary school and primary school. I talked with people all the time and I wanted to be around people! I think I noticed a change about 3 years ago... at least I recall that is when I stopped enjoying talking with people. I don't really know when this really anti-social stuff happened but it's been like this for at least 4 years now. I seriously like to talk to people when i was younger .
But later in the years I just began to feel like a wall flower ..never really having much to say and always afraid if I did say something that I would sound stupid or something. I also thought at one point I might have had agoraphobia, but I decided that that can't be because I am not necessarily afraid of social situations ...(accept for going to someone home for dinner...I hate that ...always too quiet for me and forces me to have to talk)..never comfortable in that situation. So I decided that I am just not that into being social. Don't get me wrong I like to have conversations here and there but I think I have grown to love peaceful situations...like reading or watching tv. Sometimes too much talk can create more divisions among people. But yes, I often wonder if I too am missing out on life. I wish I had that type of personality where socializing is easy and that I could be that person everyone loves to see.  I can say however that you could try and be more open to having conversation but how can you force yourself to be someone you're not...I guess you can either re-invent yourself and become that social butterfly or you can accept that you might not be Ms Talker and that you are more mello than others.....Sometimes i just cry when i think about this it made me like a sad person ever maybe i have anxiety or whatever... i hope i can change my self so i can easily have a good conversation with people.I am sixteen now hopefully i can change myself to be a better person in the future. Insyallah...

I feel sorry to the people that i avoid not because i don't want to talk it just this thing made me so quite..Sometimes i think that people hate me because of this.I always think about this and cried all the sudden  When I am with people I don't know, I don't have much to say or ask. Usually, my mind becomes blank. I feel as though I have many things I can say but I cannot put them in words.With close friends, I tend to be more social and have things to say. But with other people, I am more reserved and quiet. 
People said that i dont have to be worried about it because they said that i can change myself hopefully..