Dear Cathy Lee,

Thanks for the question.

You said:

• How can you tell God's voice from the voice of everyday life?
  

We are not trained counselors and your question really has little to do with the purpose and mission of our site: to answer questions and clarify misperceptions about the Catholic Faith.
For that reason we would highly recommend that you talk about your situation to your local pastor or a local priest who is faithful to the Church.

That said, I'll give you my personal opinion.

Any vocational calling can be discovered over time within our prayer life and by asking the simple question:

• Of all the things I have done in my life up to now, which one have I enjoyed the most, that I can also make a Christian living for myself?
  

You said:

• And if God is saying go for photography, how do I tell my dad?
  

The Catechism tells us under the paragraph titled the duty of parents:

2230 When they become adults, children have the right and duty to choose their profession and state of life. They should assume their new responsibilities within a trusting relationship with their parents, willingly asking and receiving their advice and counsel. Parents should be careful not to exert pressure on their children either in the choice of a profession or in that of a spouse. This necessary restraint does not prevent them — quite the contrary from giving their children judicious advice, particularly when they are planning to start a family.

2231 Some forgo marriage in order to care for their parents or brothers and sisters, to give themselves more completely to a profession, or to serve other honorable ends. They can contribute greatly to the good of the human family.

The Church makes it clear that your father shouldn't be exerting any pressure on your vocational choice. Your vocation is your decision, much like those who choose to become Catholic. It's the participant's choice. The Church never forces anyone to become Catholic. This is why RCIA should be viewed, not so much as a process of joining the Church, but as a process of learning the true teachings of the Church and her Divine History. After a period of understanding what the Church teaches and why, the participants can make their own decision whether to join or not, though some may have already made this decision before signing up for RCIA.

The key issue in your situation, which I can't address, is your relationship with your father.

• If you have a good, solid relationship with your father, you should arrange a time where the two of you can have some "talk time" about this. First, re-affirm that you love him as your father and will always strive to follow the fourth commandment the best you can, but that you just aren't interested in being a lawyer. Share with him the stress, anger, and emotional import of choosing a career you are not interested in. Maybe you can kindly ask him if anyone ever forced him into his vocation.
  
  
• If you don't have a good relationship with your father, I would still share with him the anxiety you are feeling over his pressure and your strong interest to be a photographer, while praying for a better relationship with him. Ask him if he would feel comfortable with you having this ongoing anxiety.

That's the best I can do.

I hope this helps,

Mike