Gender Studies is interdisciplinary but has the examination of gender and the places and roles that are assigned based on that construct in specific societies and cultures at its core. There are related but not identical areas of study of sexuality and identity in various forms. Many possible resources exist, depending on what aspects you are examining.

The terminology changes from database to database and over time, just as it does in public speech. Check the thesaurus/subject list if you aren't finding what you expect. It's very common that the vocabulary in databases lags behind the terminology in the current culture.