All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
First of all, we thank you for your keenness to spare yourself from falling into what displeases Allah with this girl whom you love, so may Allah reward you and increase your piety and righteousness.
If these expressions (or sentences) that you write about this girl include some romantic expressions, then it is not permissible for you to write about her in such a way. The jurists forbade speaking words of love about a particular woman because this may stir one’s desires and lust, and lead to immorality. The Sharee’ah has come to block all the means that lead to what is forbidden, and Satan is ever plotting against the son of Adam, so he may take advantage of every opportunity through which he can lead the person to what is forbidden. It is for this reason that Allah has warned us against his evil, as Allah Says (what means): {O you who have believed, do not follow the footsteps of Satan. And whoever follows the footsteps of Satan - indeed, he enjoins immorality and wrongdoing.} [Quran 24:21]
Therefore, instead of that, focus and occupy your time with what will benefits you in your religion and worldly matters.
If this girl is religious and has a good moral character, and you have the provisions for marriage, then approach her guardian to ask her for marriage, become engaged to her, and marry her.
Ibn ‘Abbaas narrated that the Prophet said: “The best solution for those who love each other is to marry.” [Ibn Maajah]
If there is no way to marry her now, then let each one of you go his own way, then if marriage with her has become possible in the future, then this is good praise be to Allah, otherwise women are so many out there.
Allah knows best.