Whatever you may think of yourself, you matter. You are matter. You are the glue, however small, holding everything together. Every blood, acquaintance, or complete stranger you talk to is irreversibly changed by your very existence. Without you, my own world would fall into paradox. I understand, I really do. I've lived my whole life feeling that way sometimes. Still do. But life, however lonely and sorrowful, is truly amazing. I've had thoughts but it would be such a waste of a ticket. I'm ready for anything. I'm riding this one to the very end.
In the same vein, the universe and life don't come with a preset meaning, it is YOU that provide the meaning. And meaning doesn't mean you have to give it all up and live an ascetic lifestyle while helping rebuild some wartorn place. If it is, great, but it doesn't have to be. It can be being a rock for your friends, or the person who always holds the door open, literally anything. But all that meaning and purpose had to come from you. It's what makes you human, and an amazing individual at that!