That's really impressive mate! Bulked at 18% isn't bad at all. You obviously have a good body type for building muscle as those numbers are at the upper end of what most people could achieve for your height.
I train 3 times a week on a simple chest/shoulder/tricep - legs - back/bicep routine and 3 times a week CV work. I don't have the recovery ability to train everyday, and I personally find it a more sustainable routine when you add in flight training, study and work etc. I still see good size and strength gains, but I'm not able to maintain that 'pumped' feeling you get with a 6 day split. Although by far the hardest thing I find is getting my nutrition in order, as I follow a pretty strict diet and even a slight lack of food seems to stop my progress dead in the water.
Like you i'd like to cut to around 12% as I've gained way too much BF this bulk and am probably sitting on 16-18% @ 200lbs. I'd be satisfied getting back to 220lbs and 12% again. Pretty good shape as far as my medical is concerned I think.
I think you're right about a Dr's first impression of your physique when you do your medical especially if they have to evaluate BMI. I've often been told by my Doc that many of the pilots he sees are completely out of shape, don't exercise etc. You'd think with so much riding on a medical these people would take better care of themselves!