I remember thinking like this when I was 20. I felt incomplete because I didn't have a serious relationship going, and I was somewhat depressed about it. But in the years following I had some very bad experiences with the wrong
people [unfortunately], and soon discovered that I was better off being single than being with the wrong person.
I think that it's easy to become impatient when things don't happen immediately, especially in matters of the heart. We sometimes convince ourselves that we're not "whole" if we don't have a relationship.
Yet, the advantages of being single for the early part of adulthood are actually quite powerful and useful. A single person can become a far stronger and more independent person, and consequently a far better potential mate that has more thoroughly discovered who you are and what you can do. God knows when the proper timing will come for you to be married, just as a gardener knows when a tomato isn't ready to be plucked from a vine until it's fully ripened.
Nobody likes to wait for these things- and God knows, I'm still
waiting, myself. And I've waited much longer than you have. But, I'd rather wait and be with the right person than end up with sorrow and disappointment that can only bring me grief. And the grief of being with the wrong person is far worse than the pain of loneliness, let me tell you.
Be patient, and grow as an individual and as a Christian. Be socially active. Help others. Develop hobbies. Live your life fully every day, and see that God has given you so many blessings already that you don't need to focus so intently on what you think you're missing. Open your heart and your eyes, and God will open up the skies of his blessings to you.But seek first his kingdom and his righteousness, and all these things will be given to you as well.
Surround yourself with Christian friends and activities and your desires will be given to you at the proper time, and in the proper way that only your loving father in Heaven can supply.