Did I Miss God's Will for My Life?

I recently received a letter from one who is evidently an earnest Christian woman but who was in a condition of great depression because some years ago, when in college, she felt that perhaps she was called to go to China but did not want to go but became engaged to a Christian man, whom she married, and now the old question has come up again and she is fearing that perhaps she is not saved, and may have committed the unpardonable sin, because she failed to yield to what she thinks may have...