how old are u TS?
understand that your girlfriend is underage, which checks out with her behavior of clingy-ness or requires constant reassurance and emotional security.

it's hard to maintain a LDR, i know. i speak from my own experience, but the difference is, i got sick and tired of the LDR and end up marrying her lol.

i believe you heard of the phrase "distance makes the heart grow fonder"? Age does not apply to this. it's human nature to want to be close to our loved ones.

since the circumstance is where u both have to be apart due to ur career, both of u need to have a heart to heart talk about the matter, come up with a long term game plan and share with her. u're the man, so come up with the plan. communication is key to any successful relationship be it from aquaintences to spouse.

u mentioned u spend about 1 hour ish daily to play with your phone? why not use that time just to catch up with her on her daily life and and share with her about your day as well? just simple communication. i believe all she wants is to be part of your life, knowing what happened to u today, what u ate today? whom have you met and any problems with your work today..... just keep her posted and share with her, that would make her feel she is there even though she's not , u get what i'm saying?

to be in a relationship, it means sacrifices and compromises. if u are not ready for that, then my friend, u're not ready for a relationship