Dear Timothy, 

God certainly is the Lord of history, and is able to govern it to make his will known. When he wants something he is perfectly capable of placing all the conditions there for it, but never to the point of eliminating our free will, though there are graces that "cannot be resisted". 

What I mean to say is that the fact you are not married at your age and not by your own choice could be an indication that God wants you to be a priest. If it is, it will not be the only sign; it will be there in a context of other subtle and not so subtle pointers in the same direction. The sum of all the pointers and the absence of notorious impediments will tell you what God probably is saying, but even that conclusion will not be absolutely certain - following a vocation always is an act of love, there is always some 'imprudence' and risk to it, and you can never find out for certain without actually taking the step. 

What are some of the other pointers? That you are a normal and healthy male, physically and psychologically; that you have the right motivation when you think of the priesthood; that spiritual things matter to you; that you are capable of and want to live celibacy for the Kingdom of God (in other words that your option for celibacy is not just the acceptance of a situation you don't like but seems to be inevitable). 

Yes, your age will be a factor in the decision to admit you to the seminary since the reasons for having remained single will be an important consideration in the admissions process, and something you will have to speak about in depth with your spiritual director.  

So, offer yourself to God in prayer and take a closer look at where he seems to be leading you.