Isn't it possible the reason you're closeted about being fannish is because it was your outlet and that's how the two got meshed for you? Do you think you'd be so closeted about fandom if you hetshipped? If the answer is no, then trust yourself that fandom conditioning isn't the root of your fear.

Gah, I wish I could reach through the computer and hug you. You don't have to feel ashamed. You don't ever have to feel guilty or ashamed for being gay. You don't have to be shamed of loving the fandoms you love because they help you deal with loving girls.

I honestly think the 'Catholic' bit in your secret is more telling than the notion of you somehow being 'fandom gay'. They messed with your head and left you with a legacy of guilt for not being who you've been taught you ought to be. (I know internalised homophobia is a problem not confined to one group, but there's something so Catholic Guilt about the way your undermining your own experiences here. I remember those thought patterns. *Hug*)