How do I stop being a tag along friend ??!!!!?

Okay , I am a really happy , smily , funny friend .I think people are always watching me or making notations in there head about me not in a good way , or that they remember every single thing I do wrong . Inturn I make excuses for my mistakes if people ask me and i also try not to have a certain like oppinion or anything even when i do its kind of not even recognized by people . I guess . But why am I the tag along friend ! people smile say hi if I approche them then we laugh and talk and stuff . But they wont come to me or invite me to lunch theyll say hi and they let me sit and laugh but I am never there first . I went to lunch with a niner ( i am too , ) and I went to meh friends table ( grade 11-12 's ) and she says some of them like you but the rest just think your a tag along . and its the same or even more so in my grade . What should I do ??