professional endocrinologists, psychologists and medics don’t have a consensus on these issues
What is your expertise here?
Areas of broad consensus:
Sex is a complex, multidimensional variable - chromosomes, internal reproductive structures, external genitalia, hormones, "gender" (language here is contested) all form part of sex development. These different components all have minority variations. Many of these are either naturally fluctuating or can be altered through medical treatments/ technologies, with the exception of chromosomes which are fixed (in the context of current technologies). Sex is assigned/ observed/ registered (whatever language you chose - language is contested) at birth, usually based on simple observation of genitals. For the overwhelming majority of people genitals will align with all other aspects of sex/ gender development and therefore this is uncomplicated.
"Gender" (whatever word is used - the language is contested) is a person's cognitive/ psychological recognition/ awareness/ perception/ understanding of their sex. Gender identity is something that almost all people possess, and is typically acquired during early childhood as a normal part of development. The overwhelming majority of people develop this in alignment with their chromosomes/ genitals (in the same way that all other aspects of a person's sex align). A small minority of people don't. We don't know why this happens, but we do know it happens. It is likely to be the result of a complex interplay of biological/ environmental/ psychological/ social/ (neuro-)developmental factors - although the different weighting that people give to these different factors is contested.
Why and however it occurs, gender incongruence (where gender does not align with registered sex) is not trivial/ superficial, it is a profound, pervasive, persistent, visceral psychological experience. It can be profoundly psychologically distressing / disorienting to the person when it is repressed/ denied/ contradicted etc. This can lead to depression, anxiety and sometimes even psychosis or suicide. It is highly resistant to change, and attempts to do so can be profoundly harmful. Social and medical transition on the other hand can alleviate distress.
Being trans is not wrong. It is not harmful. it does not make someone a pervert or a predator. it's a natural axis of human diversity, and has existed throughout history and across cultures. Most people are not trans, but a small minority of people are. It is not in itself a mental illness, although it can result in profound psychic distress where, as above, trans experience is repressed and denied. Trans people can live health, fulfilled, happy lives with the right support in place.
These are the main ones, but no doubt I have missed others out.