How can one remain steadfast in this world full of temptations, despite feeling love for Allah and committing sins from time to time, and repeatedly having auspicious visions?

Every Muslim should strive to be constant in obedience, for "The most beloved of deeds to Allah is that which is done continuously, even if it is little." The way to draw closer to Allah Almighty and attain His love is by preserving the obligatory acts and increasing in supererogatory ones. Among the means of steadfastness are accompanying the righteous and making abundant supplication. If a sin occurs, hasten to sincere repentance, for "All humans are sinners, and the best of sinners are those who repent," and "It is He who accepts repentance from His servants and pardons sins, and He knows what you do." As for the vow to complete the Quran, nothing is binding if it was a mere intention in your heart without verbalization. If you verbalized it, then refer to Fatwa (definition) No. 46123. As for the dreams, we hope they are good dreams.