I'm not sure if this is the right forum or if my question belongs in self-publishing.

To provide context: The secondary protagonist (she gets from 30-60% of the page count depending on the book) of my self-published Doc Vandal series is lesbian, and the second volume in the series features a romance arc for her that's worked into the main adventure plotline. Her relationship with her girlfriend later becomes the most important interpersonal relationship in the series.

I haven't used the LGBT keyword on the series and I'm wondering if that's a mistake.

What complicates the issue for me is that while she's a major character in the first volume, her orientation doesn't come up at all in that book. I don't want to use the LGBT keyword for that volume because I think it wouldn't be honest, but would it be reasonable to use the keyword for later volumes where I think it would be appropriate?

Or am I just overthinking this?