I'm reay shy and have no self confidence so it's hard for me to talk to people?

I hate how it's so hard for me to talk to people, I feel like noone wants to talk to me anyway cause I'm not worth it so I have never bothered trying to work hard at starting conversations... And I recently had a month long holiday with my aunty, uncle and cousins and the whole time I barely had any good conversations with my aunty and uncle because I'm not a hundred percent comfortable around them, but I am with my cousins cause they are younger than me... I really try sometimes to talk to people but itsso hard, I really can never think of anything to say and I always think people are judging me... What can I do to become mor comfortable around people? Also I think I have this probln because I hate myself and I hate the way I look so therefore I have really low self confidence.... :c