Dear Hilton,
It is good to talk to you. I am sorry for delaying somewhat in sending you an answer, I started almost immediately after you wrote me but I began to complicate something that is really very simple - so I set it aside and lets see if I can do better now.
An important thing to remember about God is that he doesn't speak to us only when we speak to him (like when we pray); he is always speaking to us, and in many, many different ways.
The principal way he speaks to us is through Jesus' words and example (everything we read in the Gospel) and through what the Church tells us about being faithful to him. So, when we pray and we want to hear God, we should not seek to hear new things or ask him to say new things to us, we shouldnt expect to hear voices or special messages, all we need to do is try to listen to what he is already saying, by going to the Gospel and hearing what he says there through the words and actions of Christ, his Son.
He also speaks to us through those he placed over us to take care of us and teach us his way. When you are young and your parents tell you to do something, you know God really wants you to do that, so when you obey your parents you are really telling God that you are listening to him. The same goes when a Catholic obeys the Pope, by doing so he is obeying God.
And God also speaks to us through others. If you see someone who needs help, for example another boy who does not know anything about Jesus and you try to help or teach him, you are really helping and being kind to Jesus. That's what he told us when he said anything we do to others we do to him.
So, when you pray to God about your vocation to see if he wants you to be his priest, you are not going to get an answer you can hear like any other person talking to you. But God will give you answers in many ways: when you read the Gospel and you look at what Jesus did and that makes you think of being a priest, it may be God putting the thought into your heart; or when you see how much people suffer when they don't have God and are weighed down by their sins, and that makes you think of giving your life to serve them and give them Jesus, it may be God inviting you. These are his usual ways of speaking to us. He speaks much more to our heart than to our ears.
So if thoughts of being a priest come into your mind and you want to know if it is really God speaking to you in his own way, here is what you can do to find out: speak to those through whom God is taking care of you, your parents especially if you are young, or a priest you trust. They will be able to help you understand what God is saying, and very importantly they will be able to help you see what you can do right now to be a better and better friend of Jesus so that if he does call you, you will be able to say yes and be a good priest.
I hope that helps you. Do write back if I can help you some more. I'll keep you in my prayers, especially my Rosary.
God bless.