How do you know if someone's worth going after?

21/M/USA

Long story short, girl I have become recently very close with yet known for years, through my own fault, is now located halfway across the nation.

I feel as though if I don't go after her, I'll regret it my entire life. However, going after her would involve making a very hard life decision about my future related to my career. How can I make this decision?

tl;dr I am unhappy being away from her, should I alter "life plans" to be with her? Can she be worth it?

EDIT/UPDATE: I'm flying home this weekend to talk with her about us, and to spend quality/alone time with her. She has stuff planned for us, etc. I don't know how it'll turn out. Either she'll say she can't be with someone far away or something more positive, though I'm unsure what the positive could or would be. In the meantime, please keep giving me advice. It has already helped immensely, both in how I feel about myself and about us. I need all I can get before I talk to her in person and lay it all out for her. I'll let you all know how it turns out, if you want. I don't know how much people actually care about this shit.