Is what I did, taking a piece of paper for fortune-telling, after my mother's anger and insistence on it, considered haram (forbidden)?

None knows the unseen save Allah, and claiming knowledge of it or predicting the future is a forbidden form of soothsaying. Distributing papers that contain a reader's future is forbidden, and refusing to take them is a commendable rejection of evil, provided that gentleness is observed in this rejection. If you take the paper while rejecting its content and clarifying the truth, there is no harm. However, taking it in silence is an endorsement of evil.