Question about health insurance & pre-existing conditions?

Shortly before being taken off of my parent’s insurance plan, I was diagnosed with a thyroid condition that requires expensive blood tests and regular office visits. I have applied for insurance through my job, and when reading the bylaws I noticed that it does not cover pre-existing conditions. Will my thyroid disorder be considered a pre-existing when I was diagnosed only a few months ago? Will I ever be able to get any kind of insurance coverage for this disorder now?