We are not talking about biological gender. We are talking about gender IDENTITY. Claiming that is a medical decision is absurd.
The medical procedures for transitioning are well known, and the medical community accepts that the patient, not a doctor, makes the decision on whether or not to transition. So yes, medical ethics recognizes self-determination as the accepted standard for what surgery to perform, and what result to aim for. The patient, not any medical body, makes that determination.
Right. And misdemeanors (and felonies) have zero to do with what people feel about the issue - they have to do purely with whether someone violates the law. There is no doubt that in North Carolina, you could throw someone in jail who used the wrong bathroom - just as at one time, you could throw a black person in jail if they used a white bathroom. The law stated both of those things were illegal. And there is no doubt that an angry cop could charge you with a dozen crimes if you were to do such a thing (or were black, or Muslim, or whatever other factor made him dislike you.)
Further, I have no doubt that you could find a great many people today who would be uncomfortable if a transgender (or a gay, or even a black) person walked into the bathroom they were in. However, as I mentioned before, that does them no actual harm. A man who goes into women's room claiming that he is really a woman for the purpose of raping them - that is clearly harm, and if that were frequently the case, I would support more stringent laws on bathroom gender identity policing.
Until that is shown to be the case, though, it is simply a non-issue.