I'm thankful you realize that getting married is a serious step, and that you want your marriage to succeed. Far too many couples today, I'm afraid, say to themselves that if their marriage doesn't work out, they can always get divorced and try someone else. But that kind of marriage lacks the one thing that could make it succeed: commitment.
The most important thing I can urge you to do is to seek God's will for your future. God loves you, and He knows what is best for you. He also knows all about you, and He does not want you to make a mistake in this all-important decision. Ask God to guide you and make His will clear to you–and then be willing to follow it. The Bible says, "As for God, his way is perfect; the word of the Lord is flawless" (Psalm 18:30).
Let me suggest that you seek out a few trusted friends (such as your pastor) with whom you can share your concerns–ones who are older and more mature, and who also are wise and spiritually sensitive. The Bible says, "Plans fail for lack of counsel, but with many advisers they succeed" (Proverbs 15:22).
Most of all, make sure of your commitment to Christ–and that of your future spouse as well. Make Christ the foundation and center of your life, and He will not only guide you in this decision, but He will help you and your spouse build a marriage that will last.