I am a 19 year-old (almost 20). I have erections often (which I believe to be normal for my age.) I have a wet dream probably once a month. I'm wondering about something, though. The only times that I have orgasm or ejaculate are during wet dreams (while I'm asleep, they obviously wake me up). I've never had orgasm or ejaculated while being awake (which is not a bad thing, so to say). I'm just wondering, am I going to be able to have orgasm and ejaculate when I see my wife in a few years?
Everything you stated is completely normal. You're going to have erections for the rest of your life (barring problems caused by diseases). They will decrease in frequency as you get older because your brain will eventually get the idea of when is the proper time for having erections. During the night you will continue to have four to five erections, corresponding to the Rapid Eye Movement (REM) cycles of sleep. These erections are believed to be necessary to keep the penis well oxygenated and the passageways clear so erections can happen when needed for sexual intercourse. Most mornings you will notice the last one that comes just before you awaken. An absence of nighttime erections for a period of time is an early warning that you have something seriously wrong with your body. As a result, some people joke that these nighttime erections are a part of a man's automatic systems check.
While the frequency of wet dreams varies quite a bit between men, once a month is fairly typical. Once you are married and are having sexual intercourse regularly, these wet dreams will stop, though they will restart if any circumstance causes an absence of sexual intercourse for a period of time.
The fact that you are having orgasm and ejaculations means all your systems needed for sexual intercourse are in good working order. You won't have any problems when it comes time to have sex with your wife, other than the typical awkwardness of figuring out exactly how to have sex. You can read about it and talk about it, which will help you avoid some of the typical mistakes, but it is nothing like experiencing it.
Wet dreams serve two purposes. The obvious one is to get rid of the old supply of semen so there is room for a newer batch, but a second reason is that it gives your brain and body many chances to practice the coordination of the various internal systems needed to have sex. If you think about it, it makes sense in God's design that sex is not completely novel when two people come together in marriage for the first time. At least one half has a rough clue as to what is going on, even if it is mostly instinctive.
Under the Old Law, there was an interesting rule for newly married couples: "When a man has taken a new wife, he shall not go out to war or be charged with any business; he shall be free at home one year, and bring happiness to his wife whom he has taken" (Deuteronomy 24:5). I find it interesting because the law states that a newly married man's duty is to give his wife sexual happiness, but nothing is stated the other way around. Yet, if you consider it a moment, if a husband can please his wife his personal pleasure is assured.
The reason for mentioning this is that young men instinctively know how to get to orgasm, but they have no practical experience in giving their wife sexual pleasure. What I recommend is either finding a Christian man (preacher, elder, or someone you trust) who is willing to discuss and answer your questions about sex, or lacking these find a decent book on the topic. One that I can recommend is called The Act of Marriage by Tim and Beverly LaHaye. I've also written a small book, not nearly so detailed, called Preparation for a Lifetime that can be useful. There is no rush, but plan on studying the topic about six months before you get married.
In the meantime, take some time to study the Song of Solomon. It is designed to teach people about romantic love and it will help you greatly in these days of courtship that are coming up. See The Greatest Love Song Written.