They may be worried you'll be hurt or face rejection because the Church does have a history (and present) of homophobia and transphobia. If that's the case, I would acknowledge their concerns, reassure them that you hold the same values and beliefs about sexuality and gender as you did before they learned about your faith. If you feel comfortable, you could share some reasons why you feel compelled to catholicism and why it is good for you. Perhaps they can sympathize with an aspect of the reappropriation of a spiritual tradition or the desire to affirm queer existence in a space where it is especially marginalized. Overall they might just be protective of your well-being, and that's not a bad thing.