Oh yeah, that sucks. I mean seriously, saying good bye to anyone close is hard, but nothing is harder than to say good bye to someone you truly like/ love. I get that. I think it is really up to you and your ability to deal with hard good byes. I am really bad at this, some of my friends are better at this. If you do not know yet and you really have chance of starting a relationship with her, do it. You need to make experiences to succeed later on in life. We are in high school.
If you have had bad experiences before, I would recommend to avoid it. In the end, it is really up to you, her, your chance of starting a relationship and your ability to deal with that kind of situation. Some people cannot even deal with the thought of being separated in some period of time. If one of the partners thinks that way, the relationship is basically doomed.