Dear Dan,

I think you should take some steps to get more concrete as regards your vocation. Right now you are pretty sure it is the priesthood or some form of religious life. That leaves the field wide open, so it is time to start investigating.

If your thoughts of the priesthood include serving in a parish you should get in touch with the vocations director or bishop of your diocese. If you know that your call is not parish ministry but definitely to a religious order (although you are perhaps not sure if you should be a priest or a brother), start looking into the religious orders you know about, especially if one of them attracts you in a special way.

Otherwise, do some searching on the web. When something catches your attention, follow up on it. Find out more and speak to the vocations director from the group. This is the usual way of finding out what God has in mind for you.

As regard studying philosophy, I would recommend that you do so with some guidance, since a lot of what is called philosophy in college is more a history of philosophy, but without the systematic search for truth and often with a strong bias against metaphysics and a sane epistemology, since relativism is the orthodoxy of the day. 

Many diocesan seminaries and religious institutes do philosophy as part of their formation program, and I think that overall the better route is to go give priority to investigating your vocation, and then with the vocation director of the diocese or religious order you settle on, work out the question of your studies.