It seems to me that her response is not about not believing you, but about enlightening you to how babies and children survive. They cannot survive on their own, so they must trust to survive.

Having to trust a primary caregiver who is not nurturing and loving and protecting forms the pathological or 'sick' attachment that causes problems in all relationships, because all relationships need trust and we form attachments. You can imagine that an infant or child who must trust to survive, but for whom that trust relationship is not nurturing or loving or even kind, gets a confusing picture of relationships. When the primary caregiver is unreliable, unpredictable, unTRUSTworthy, the attachment is insecure or disorganized. The infant or child trusts only when necessary (for food, etc) and retreats at all other times.
We are amazing creatures who understand more than we can imagine, even pre-verbally.

Does this make sense?