Hi Ashley
To a certain extent our perception is the reality that we live in. Ask yourself what is it that makes you who YOU are? What defines you?
Is it purely your chromasomes?
Is it your body and what lies between your legs?
Is it purely your mind?
Or is it some combination of all these things and a whole lot more that I haven't even begun to list.
I suggest that it is the latter.
So even if this is, as you put it, "a delusion" that delusion is a part of who and what you are and therefore your delusion is in fact at least in part a reality.
I too felt like you did. I too first expressed it at an early age. I was even allowed by my parents to indulge my fantasy from that age to the point where, when I eventually sought medical help aged 17 the specialist insisted that I try living for a period in my natal sex before he would allow me to progress. He figured that perhaps he could alter the way I felt.
But the flaw in the idea is thinking that you can change something which is a fundamental part of who you are? You can't - if you weren't trans then you would not be you, you would be someone else. Or to put it another way, I may indeed be crazy, but if I am then to be honest I quite like being crazy so I don't really want to be sane.
The old addage that you can lead a horse to water but can't make it drink also applies. Back in the dark days of the late 50's and early 60's various psychiatrists tried giving aversion therapy to gender patients. What the found was that the patients mostly became suicidal because they effectively became averted to themsleves - they HATED themselves and many of them took the logical way out.
The program was rapidly stopped and indeed the results became a part of the early justification for doing sex reassignment surgery.
Bottom line, I don't believe it really matters whether it is a delusion or not as long as you are happy living with the end result.
For years I lived with the knowledge that it was very likely that my condition was all in the mind,only to discover, years after it had ceased to make any practical difference that there actually was some physical basis and I had in fact had an undiagnosed intersex condition all along. I'm not saying that this will happen to you. The point I am making is that in this world very few things are absolutely certain.
Medical knowlege is constantly advancing as this
http://www.telegraph.co.uk/health/3265125/Gene-could-hold-key-to-why-transsexual-men-feel-female.html story shows.
So in the end our gut feeling, horribly uncertain as that is, is often the best guide to the right course that you have.
I hope all that helps at least a little.