I don’t know based on what we know I wouldn’t say she’s a lesbian though, she does identify as gay but it’s in a very specific context where she’s calling out John on his bullshit (or more like refusing to let him hide behind his “I’m not gay” default answer because, as we’ve argued many times, in this specific context it only eliminates one sexual orientation and says nothing about his attraction to Sherlock). I’d say bi/pan/poly who knows? If she’s supposed to be John’s foil, which she is, I would say that bi makes the more sense but we don’t know enough to draw definite conclusions. 

I would def rule out lesbian though because she is instantly attracted to Sherlock (we can see it very clearly when we have the whole sequence with her hand caressing sherlock’s pictures at the beginning of asib) and tbh I’m as much of a fan of the “gay with an exception” trope as I am of the “straight with an exception” trope which is: none at all. 

Irene is hard because her work definitely involves sex and even though we know that she apparently sleeps with men we definitely don’t know to what degree she is sexually attracted to other genders than hers. I guess every orientation is pretty much open except strictly gay or heterosexual.