Gender critical feminists are a subset of sex realists. If you are gender critical, you first have to believe in the reality of sex.
Saying you are a sex realist rather than gender critical implies to me that you don't hold gender critical beliefs (these are defined in@POWNewcastleEastWallsend's post) . Is that the case, or are you also gender critical? In case that's still not clear, someone like Trump is a sex realist, but not gender critical.
You said earlier that you didn't fit into the Venn diagram posted by a PP. I'm not sure how that's possible so I asked you for your position on the 3 statements and their opposites which were included in the diagram, but you declined to answer. Would you be prepared to answer them now?
Do you think sex is nonphysical/changeable or that sex is physical/non-changeable? (I think I know your answer to this as you call yourself 'sex realist'.)
Do you accept or reject gender nonconformity?
Do you think gender is oppressive/constructed or that gender is edifying/innate?
Perhaps you are a sex realist but not gender critical (like Trump) and that's what your objection is to the term gender critical - that you just don't agree with it. That's your right, but you keep referring to 'we' as though you are gender critical.