I do believe most people can get through much more then they think they could.
But not all emerge the way you did. Some turn bitter, some give up. You should give yourself credit for not only overcoming everything that has been thrown at you, but SHINING!!
It will make a big difference for you to learn to understand the "introvert". Not many people do, unless they are one themselves. Time to be alone IS important. Having days when one doesn't want to talk a lot is not meant to hurt or that something is wrong.
Its just a way to recharge batteries. Its a true need. The best thing you can do is to understand and give space. It is a true gift to not only understand but respect each others differences.