There's a girl that has my number and i keep telling her to text me, and she says she will later but she never does. I also invite her out a lot.. am i coming off as needy?

Nah...

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“Nothing is impossible, the word itself says 'I'm possible'!” ~Audrey Hepburn

Yes. Never try cajole someone into texting you or hanging out with you, it always smacks of desperation. Instead let the person come to you of their own volition. Give her a reason to want to reach out to you, do this by being light and playful with her. If ultimately she doesn't contact you she's not interested.

Yes you are from "i keep telling her to text me."

Here, you want to play with the texting. I have made girls, who would not have gone out with me if I haven't been doing the constant back-and-forth texting to build the attraction and get her interested.

Be playful and fun. Show her your personality, then go for the "ask out."

She'll text you if she wants to. If she doesn't, she doesn't want to. Pretty straightforward.

Yes your coming of as very needy. Don't ever keep telling a girl to text you, you should have the balls to do that. However occasionally I tell a girl to call me later as a test to see if she will. If she doesn't I know it means that I need to game her more but I won't repeat the same thing. If she never does, there's no point it continuing to ask her, it will get annoying quickly.

Don't invite her alot, thats needy too. I found that its better to invite her when you know shes interested in you. And when you do, don't do it so directly. Say something like "Man im so excited for next week, me and a group of friends are going ______, I can't wait for that!" (she will expect you to invite her also, but instead talk about some other stuff) then before you end the conversation say "oh you can come along to our thing if you want."

If you think you are, you are. In this case, you are.