I cannot tell you what the future holds for you, but I can tell you that millions of people share your fear. However, studies show that about 95% of people get marred by the time they're 55 years old. I know you'd rather not wait that long, but at least you can rest assured that only 5 percent of the population lives that long without having been married.
I can't tell you what the future holds for you, but I can tell you that many people see marriage as the solution to loneliness. It is not. In fact, if a person cannot learn to be content living as a single person, I highly doubt that marriage will cure their discontent. Indeed, the idea of being loved unconditionally is appealing. But while a person is single, it is more important that he or she learn to love others unconditionally, beginning with one's one friends, family members, and God. If a person does not experience love at home or with friends, then marriage is not the solution. The solution may be to find better friends, to deepen your relationship with God, and to work on healing one's family issues. After all, you can't build one family upon the ruins of another. If you are able to practice loving others and you surround yourself with those who do care for you, then the single years of your life will not seem so lonely.
I do not know how old you are, or how long you have been struggling with this. But check out these words of encouragement by St. Francis De Sales:
"The everlasting God has in his wisdom foreseen from eternity, the cross he now presents to you as a gift from his innermost heart. This cross he now sends you he has considered with his all-knowing eyes, understood with his divine mind, tested with his wise justice, warmed with loving arms and weighed with his own hands to see that it not be one ounce too heavy for you. he has blessed it with his holy name, anointed it with his grace, perfumed it with his consolation, and taken one last glance at you and your courage has sent it to you from heaven, a special greeting from God to you, an alms of the merciful love of God."
So know that God is with you through this difficult time. Only he can satisfy your heart. For example, a good friend of mine is over 50 years old, and has never been married. I'm sure she experiences loneliness at times, but she radiates such joy because her life has become a gift for others. In fact, she is more joyful than any married person I have ever met! Her heart is at rest in God alone. She knows that nothing but God can sustain her in peace. When we look to people, or even to marriage, as the solution to all our pain and loneliness, we can begin to make an idol out of it. When people do this, they often enter bad marriages, or become depressed because marriage has not occurred.
To help prevent this, go to a good Christian/Catholic bookstore, and look in the section for dating, singles, and young adults. There are several good books out there that specifically address the single season of life, and how you can make it some of the best years of your life. After all, God may call you to marriage in five years, and you certainly don't want to be miserable until then. Maybe he'll call you to the religious life and you'll be thrilled to have Christ as your groom. Only he knows the future, and so now you must focus on him alone.
Lastly, read Jeremiah 29:11-14 . . . and be assured of my prayers.