Correção de texto: "I knew how it felt to be an outsider"

I knew how it felt to be an outsider

It's very common in school classes students organize themselves into closed groups of friends. I not used to be popular at school, but I at least used to belong of a group. However, it was not always so. At one of the schools where I've studied I started later, when all group of friends were already formed. There, I knew how it felt to be an outsider. Luckly, the classmates were very nice and I slowly got to become friend with them throught the year.