Friends ?

So its these groups of friends i have at school . Its 4 of them but it feel like im the odd ball . They have a group chat which im not in . If they leave campus for lunch they text the people in that group of 4 & they go eat nobody text me or even tell me knowing we suppose to sit at the table . & everyweek if they go out or hang out or like make plans to go eats , smoke movies or something its only them nobody ask me to hang out .. so they wouldnt be my friends right ? I should just leave them alone ? Stay to myself .. i dont really like looking lonely at school