Yes, read that study. Mildly interesting, slightly suggestive but as you pointed out post mortem and sample size way too small to be meaningful.
There is a well known person, a trans woman, who posts all over the internet. She is a rocket scientist, just ask her and a self appointed expert in all science matters, studies, material, theories etc ad nauseating when it comes to the so called transsexual condition. She even invented a whole new syndrome to explain her sudden and spontaneous change of sex when fully mature and in her (i think) thirties. Heck, she might even be right.
For some, this knowing or trying to know why the have the feelings they do is very important. They need an explanation and will invest all kinds of efforts trying to find one. Like the one that has to do with that di whatever it is med that women took during pregnancy. Might be true for all I know. Im not a scientist but I can read and I have a working sense of smell.
All kidding aside. Its fine to be curious, I sometimes have the same curiosity. But all the well adjusted trans people I have ever met just dont care. Anytime someone takes an unusual interest in this topic they are telling you something about how they feel about themselves. If you are transsexual, you will know. You will either come to terms with it or not. If you get stuck, worrying that it may be some kind of moral defect then its not surprising you might want to invest unreasonable amounts of time desperately trying to find some other reason.
For myself, I could care less. I am what I am and I am okay with it. I dont know why I am this way, I just know the way I am. Thats all I need or care to know. Nothing anyone says, writes, researches or says will change that.