Dear Eric,

I think this is a good opportunity for you to go really deep in the consideration of your vocation. Your parents have their reservations for humanly prudent reasons, and so their opinion cannot be summarily swept aside, you have to give it the consideration it is due. However, at the same time your feeling that God is calling you is pretty strong, and your heart is telling you to come out of college and enter the seminary now, so that also has to be evaluated.

First, I think you should keep in mind that as a seminarian you will do college studies. Of course they will be studies that will form the basis for your later study of theology, and so they will be heavy in the area of humanities and philosophy, but they are college studies none the less. Check with your diocesan or religious vocation director (depending on where you are thinking of joining) to make sure this is so.

Second, I think you have to give a little more substance to what your heart is telling you and to these strong feelings you have. What I mean is, feelings and the inclinations of our heart tend to be fickle. Sometimes even the weather is enough to influence and change them! Or a retreat, or a temptation. So, you need to take these feelings and examine to see what they are based upon, what causes them and when they come more strongly to you.  It may take a little more work to distinguish if they are purely emotional feelings or spiritual feelings / hunches, in other words a spiritual reaction to a situation you perceive (you see people who need God, and feel the desire to do something for them). Spiritual feelings tend to have a longer life-span and be more insistent than purely emotional ones, and they are very indicative of the way God is working in our soul. You will find it very helpful to have the input of a spiritual director as you tackle this part of your discernment because obviously at times it can get confusing.  

On top of this, you should reflect on your motives for thinking you have a vocation and for wanting to be a priest. The more centered on Christ and others these motives are, the more genuine they tend to be. Make sure also that in your life there are no indications that God does NOT want you to be a priest (what we usually call impediments).

And pray. Ask for enlightenment but above all ask for the grace to be generous and to love Christ authentically, and for the grace to be ready to embrace the crosses and sacrifice that being a priest entails.

So you can see, it is not a question of choosing between your head and your heart. It is a question of using both, and making sure that you leave the door of your mind wide open to the light of faith, and the door of your heart open to the gift and promptings of love.