GF [23F] of 1year doesn't know if she wants a serious relationship[28M]

Been dating my GF for 13 months now. Long distance, she was in college 4hrs away for 9 months, then 1hr away for 3 months, now she's 4 1/2hrs away for her 6 month internship. When her internship ends, I'll be getting out of the military and the plan was to move to the same city, if not into the same place and go from there.

Recently she's been worried she's not ready for a serious relationship. She is young. Never really been on her own. She's living alone for the first time while at her internship and loves it. She is worried because these feelings came up about 4 months ago but she just dealt with them and moved on. But now she's worried this will be an ongoing fear.

I guess she's just worried about being old with me one day and realizing she doesn't know how to be alone? Anyone go through this issue? I told her to take a week to think about it, without us talking.