It’s okay to be shy, it’s your personality. As long as that doesn’t ruin your daily life, which i assume it does from what you told me. I relate to what you say (eye contact, feeling embarrassed, getting scared) to the point of having panic attacks. But that’s something you can change with time. Try small things first, and then go up. Sometimes it’s hard to keep a conversation going, but give it a shot. Ask questions while talking to people, talk about something you know another person likes, or if you share interests with someone talk about them. Small things. Then you can move to bigger things like the eye contact and speaking in class without feeling embarrassed. Work on it slowly and don’t let your shyness win.