I have a question regarding marriage. I like very much the idea of adopting, I am 22 years old right now, but I can't wait to adopt! I know, I know, I must first secure a good home for the children to come; that is why I am studying both a career and the Bible (but I feel my Bible study is a bit weak, another topic for another day). How do I know I am meant to get married? Or let me rephrase that: How can I be sure I am marriage material? Someone once told me some are meant to be single and others married. If true, how would I know to which group I belong? I would like to be married. I would like to have and adopt children, but I would also understand if, somehow, I would be told by God that such is not my mission and that I have other things to do.
It is not God who decides whether you marry or not. God gave all people the choice to decide whether to marry or to remain single. In explaining to Christians of his day that persecution would make being married rough, Paul said:
"I suppose therefore that this is good because of the present distress -- that it is good for a man to remain as he is: Are you bound to a wife? Do not seek to be loosed. Are you loosed from a wife? Do not seek a wife. But even if you do marry, you have not sinned; and if a virgin marries, she has not sinned. Nevertheless such will have trouble in the flesh, but I would spare you" (I Corinthians 7:26-28).
Notice that while at that moment, remaining unmarried would be the better choice, Paul makes sure the Corinthians knew this wasn't an order. God gives everyone the choice to decide whether they marry or not. That choice, however, produces consequences. For example, it is a sin to have sex outside of marriage, so choosing to not marry means choosing not to have sex. For many people that is too hard to follow. "But I say to the unmarried and to the widows: It is good for them if they remain even as I am; but if they cannot exercise self-control, let them marry. For it is better to marry than to burn with passion" (I Corinthians 7:8-9).
Since you want to have children, then you should seek to get married. Whether some woman considers you marriage material will depend on how well you prepare yourself to live with a woman.
It is a false notion that God dictates every choice that man faces. God gave us free-will. He makes use of us to accomplish His will, regardless of what we personally choose. See: What do you think about predestination and free-will?