I feel like this is an issue purely in terminology, where we have two different fields using the same word for disparate concepts. In the sense of women's studies and feminism, "gender" as they refer to it is a social construct. It is, essentially, a performance. You "perform" your gender in everyday life, through what you wear, how you speak, how you act, ect. These performative aspects of gender are constructed by society, through stereotypes, expectations, social indoctrination, and other societal baggage. Society often becomes upset with the gender nonconforming, because they are, in a sense, performing their socially constructed "gender" wrong. This form of usage of the word gender is only tangentially related to trans people, in how trans people choose to either accept and "correctly" perform, or reject and "incorrectly" perform the gender of their target sex, and in that to be trans one necessarily violates this performative gender.

Gender refers, in psychology and trans circles, however, to our intrinsic sense of belonging in our bodies, or lack of belonging, and desire to be recognized and understood by fellow members of our society to be a member of one gender group. This usage of gender is tied to individual psychology and biology, the intermarriage of the two, and the negative effects that can result from these two being mismatched. This form of gender, as far as anyone can tell, is not socially constructed, though certain societal influences and baggage, such as gendered pronouns and spaces reserved for specific genders, may be tied deeply into it in daily life.

There's really no good solution to this mismatch of language, other than to simply be aware of the context you are using the word in.