I was brought up by parents to just accept facts, and one of those facts was that you can't change biology. But I knew, from a very young age, my biology was messed up and my gender was not what they all thought it was. Back then there wasn't the dialogue or information out there about trans issues as there is now. I had heard of sex changes but I had no idea it was something *I* could do. I thought it was something very rare that only people with immense problems could ever have done. That is the fault of there being so little information out there... and it was also before the 'internet age'. I blame myself for not being more astute about myself earlier, but then again I was struggling with depression, anxiety and massive unhappiness in general. It is hard to see clearly in that situation.
People don't want to hear this stuff in everyday talk so you suppress it, try to forget about it and live a 'normal' life, and before you know it 15 years have passed and you're as unhappy as ever with the same reality. Eventually it dawns on you that you have a problem, have always had a problem, and just haven't been able to understand it fully with the right words and connections until now. And then you hit the angry phase, followed by the "I better do something about this before it's too late" phase.