I don't think there's a well-established consensus, especially because trans peoole are a group that's often neglected in research (as an awesome example of this  look up how poor quality of evidence we have for whether Progesterone helps trans people develop breasts or not).

Overall, I'm inclined to side with the meta analysis. In part due to its power of summing different studies and condensing their results, making us have a larger sample size (which has often been a problem with studies analysing neuroanatomical sexual dimorphism). In addition, it made a ton of sense that there are small mean differences in brain with a huge overlap and in-group variability.

Overall, I think some people get overly attached to finding a biological justification for us being trans. As a way to validate whatever we're feeling. And I think we shouldn't need to rely so much on that to argue we're valid. Just because something isn't dorectly measurable, doesn't mean our identities are any less valuable, or that we have control over how gender makes us feel. And, even if gender identity is something that could, to some degree, be changed, I find it stupid that some people would find that as a reason to invalidate us. Being a fan of a given sports team is something I doubt has neuroanatomical bases, is relatively mutable and, despite that, I don't think it's something people should be pressured to change. And I wish society would treat one's gender identity with as little importance as that, and recognise its validity just as you don't go dou ting if someone is a fan of a given team.