The science of astrology is based on the reading of the stars and planets, their movement and how they affect each other.
It is considered a superstition because of the lack of significant astrological predictions, and yet it is widely spread and people believe in its predictions, so it is lastly considered to be "pseudoscientific".
It is easy to explain something after it has happened, in any kind of ways, using any kind of meant.
You see teens everywhere read their horoscope and I believe that it does affect the turn on events, psychologically in their lives to the way it is predicted.
There are predictions that come true and there are that don't. It seems like a guess-work, but those people are in a way trained to read the signs of their 'customers' and based on that and the logical info you get from the questions asked, you can make a fairly accurate prediction.
That is, of course said when you go and visit them. Those, that personally see you, rarely make bad or negative predictions to skeptics, because they do want to remain in good graces with them.
Having a prediction, based on astrological chart, via the internet is probably more like gambling then facts. There are information about the typical age and appearance of the human that ask for those charts, and based on that it will probably make a good guess. In your case, even if you have a interesting life, or not, it is probably similar to most of you peers. Those predictions about the basic things as love, career ... are said in a way so most of the people that will read it, will find themselves in it.
It is, lastly up to you if you want to believe in it or not. I would say it may make a difference in you lifestyle, hopefully good, but it is all based on the power of suggestion.
I wouldn't put too much credit on it, however.
I hope this helps :))