Is it normal that you think a lot?

I have never been a social person when I was young. Then I went out of my town to study. I didn't make many friends because I wanted to study hard. So I was lonely all the time. It was during this period that I started becoming dreamy. I dreamt all the time, with open eyes,literally all the time. There was always a conversation going on with myself in my head. I could not concentrate on anything because I was busy talking to myself. It began to get even worse because my grades began to fall and I could not understand the reason. I was really depressed. I went through this for like 3 years. Then I accidently made some friends and felt better. And now, i'm just okay. So have anyone of you ever had so much talking going on in your head?