Answer:
Your vow was foolish. God commanded that everyone abstain from fornication. You don't have a bargaining position in this matter. "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4). By making this vow, you basically said you would only obey God if God did you additional favors. It was no longer about you bending your will to God, but you demanding that God bend His will to you. Thus, you committed two sins: one, to think you could bargain with the Almighty, and two, disobeying His command by having sex outside of marriage.
I'm glad you've turned back to God. But serve Him because it is your duty. "Let us hear the conclusion of the whole matter: Fear God and keep His commandments, for this is man's all. For God will bring every work into judgment, including every secret thing, whether good or evil" (Ecclesiastes 12:13-14).
"Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him. For all that is in the world -- the lust of the flesh, the lust of the eyes, and the pride of life -- is not of the Father but is of the world. And the world is passing away, and the lust of it; but he who does the will of God abides forever" (I John 2:15-17).