Almost a year ago I felt a huge urge to meet Amma, so I did and also had a mantra from her with instructions. After that meeting I have been "seeing" Christ and now feel that I want to follow His teachings, but am I than unfaithful with my Guru Amma? When I was on the gathering they said that it can be good to read from her daily and pray to her for protection, but I now feel confused, because Jesus said that I should love Him with all my heart.
This is an important question and the answer must ultimately be found within you. Try offering your confusion into the flow of inner understanding, for that is clearly the process unfolding here.
If you accepted Amma as your Guru (to the best of your knowing and of an open heart), then ask her inwardly how to receive the inspiration you are experiencing through Jesus Christ. Meditate on this and inwardly seek clarity and understanding. “To love God with all your heart,” means to deliberately put all your energy into seeking Him.
Discipleship to a Guru is a profound and eternal relationship. True gurus are not in competition for you to be their disciple. The Guru is God-given. Until we have this depth of clarity with our Guru, others help us to prepare and receive. Be grateful especially that you have such Great Ones in your life.