Na, u lost her...why would you just walk by her and only say hi? That makes it seem like you guys barely know each other. and then with the text messages you sent, it almost seemed like you were not comfortable enough with her to stop and talk to her when you saw her and you only had balls to make a move through text.
If you get a girls number through warm approach (i.e. school, work, mutual friends etc) then calling the next day can be a little needy. Now, calling the next day is practically NECCESSARY a lot of the times for COLD approach, but not for warm approach.
And the first text you sent her "hey whatsup XXXX" is not a good text. Its boring and what every guy does. You gotta be a little more interesting than that.
"Hey XXXX, make or break question. Smores or cheez-its?"
or even "OMG something totally just reminded me of u. I'd explain, but you'd hate me

"
something along those lines... OR you could even just say hey whatsup if you had given her a nickname, cuz thats always fun. I always give girls nicknames when I first get their number. Ill be like "OK I'm putting you in my phone as Jessica the psycho murder" or "OK I'm putting you in my phone as Crystal the gangster kindergarten teacher" Its always different cuz it always derives from something I teased them about or something I noticed about them or whatever but its always stupid and playful. SO that way even if i do just say "hey whatsup XXX" its ALWAYS more interesting cuz instead of "hey whatsup Jessica" its "Hey whatsup Jessica the psycho murderer" and that gives her something to play with, so she'll usually have fun with that and play back with me. I did that today with this girl I was texting for the first time and we went into this whole role play about how we're gonna rob banks together and stuff. Get it? FUN.... Hope that helps.
But I also think you just need to get out there more and meet more girls.