Just after leaving the Golden Saucer (and finishing the battle in the jail with Barret) I went over the river heading towards Cosmo Canyon and found Yuffie in a forest while riding in my buggy. After playing in the forest and going through the special encounter with her a few times (happened every 3 encounters) I got her to the point where I asked her to come with me. I choose the wrong option by trying to name her instead of saying "let's go", then she disappeared and said she'd never join me.
Since then I've tried to get the encounter again in the forest while in my buggy but after more than 30 tries she hasn't shown up. Have I lost Yuffie forever? Is there another place I need to find her now?