I don't know who said this, but there is a quote to the effect that we regret most the things that we have not done, rather than the things we did. Pursuing a childhood dream is not a vanity, IMHO. I did it myself. Ask yourself how you're going to feel 10, 20, 30 years down the line. Can you see yourself using your degree with satisfaction and pride (not always a dirty word!)? Do you feel like you would be fulfilling God's will by doing this work? Not easy questions to answer. I'm not great on giving advice but I think you should stick with the program until you are sure of your decision. No harm, no foul. And keep on praying, especially to the Holy Spirit.
Prayer for the Gift of Wisdom
Great is the wisdom of the Lord!
God Almighty, Your Wisdom includes
An understanding of what is fair,
What is logical, what is true,
What is right and what is lasting.
It mirrors Your pure intellect!
I entreat You to grant me such Wisdom,
That my labours may reflect Your insight.
Your Wisdom expands in Your creations,
Displaying complexity and multiplicity.
Your Wisdom is an eternity ahead of man.
May Your wisdom flourish forever!