Dear Barry, 

I think if you have a vocation there are two signs that you have found where you are supposed to be. 

One is that you feel "at home" there. This is logical, since your vocation is what God meant you to be when he created you, so obviously when you are where he wants you to be you have the feeling of being made for there, which you were. 

But I think it is also very important that you feel like it is just a little too much. If you don't you are either in the wrong place or you haven't understood what it is all about. 

You see, God always calls us higher. When you are where God wants you to be you realize that you are not going to be able to do this on your own. You need his grace, it is going to cost you, you are going to have to die to yourself, you are going to have to make choices, there are things you like that are now going to have to take second, third or fourth place, or have no place at all.... The second sign then is that tremor of fear. You could say it another way, you could say that you have found your call when you discover that you are really going to have to work to make it a reality. Your vocation is not something you discover and slip into comfortably and effortlessly. It is going to take all the qualities you have (both spiritual and human) and make you stretch and develop and use them beyond what you ever thought possible. Because God wants you to be a saint, and that is the challenge of a lifetime. 

God bless.