JakeD, the problem is you were prescribed an inhaler after the age that would not start the ball rolling.
Nobody can prove that you ever or never used it, thus they most likely as you read:
d. Asthma (493), including reactive airway disease, exercise-induced
broncho spasm or asthmatic bronchitis, reliably diagnosed and symptomatic
after the 13th birthday, does not meet the standard
will look further into your records. It may be a remedial, which may than include more testing to prove you are okay. If you got an inhaler filled when you were 15, you fall under what I just quoted does not meet the standards.
There is no need to bring a letter to this 1st exam, you were under medical supervision and you filled the prescription at 15 or so, it is in your records. Again, your doc cannot swear that you never once used the inhaler, all he can attest to is he prescribed it.
Be prepared to jump for the moon if you don't get a DQ, jump for joy if they allow you to start the waiver process and/or ask for a remedial. Otherwise, it is all out of your hands now except for getting your records in order now. I can't tell you what to do, but you know it is there on your records as Asthma after you were 13, you can see in the threads I posted over and over again the same reg.
Just me, but if I were you I would look back in the links I provided and start asking about the spirometer test that is used for this medical issue regarding remedial and waivers.