Go here for a great explanation on sex, marriage, why contraception is wrong, and Natural Family Planning. God is not the big spoilsport in the sky. He gave us love and marriage to generate new souls for heaven and to help us to be happy here on earth. If you follow his rule book you have a better chance to succeed in your "pursuit of happiness." Catholics who follow Church teaching on marriage don't get STDs, have a much lower chance of divorcing, have a lower risk of contracting breast cancer and other diseases associated with artificial hormones, etc.
If you bought a Porsche wouldn't you read the manual from cover to cover to make sure you did everything necessary to keep it in good working order? Well....you ARE more valuable than any Porsche and if you want to keep yourself and others in mint (baptismal) condition, it's not that hard. Read the manual and follow its directions. What's the manual? Scripture, the Catechism of the Catholic Church, writings of the Church Fathers and the saints.
Life is an exciting and wonderful adventure. You will enjoy it the most, if you follow the rules set down by the "life coach." Don't let the lies of the enemy mess up your adventure. It can easily become a nightmare that way.