The thing is, your mom is worried about you dying at Armageddon. If you were and atheist, that would be bad enough. But as a Christian you have found an alternative faith. She can’t offer you hope, because you already have your own hope. So her fear and sense of frustration manifests as anger and criticism.
That is how she shows her love, in the hope that her opposition to your decision to not be a JW will change your mind. She loves you and is afraid of losing you.