Drugs.
Seriously.
Talk to your GP, get some nice meds for motion-sickness (bonus points if they make you drowsy as well) and tell him that you have a flying phobia and ask for a prescription for just a pill or two of something like Xanax.
Best stuff ever (in my experience) for temporary blanking of inconvenient phobias. It’s hard to describe - you’re still aware that you’re in a situation that you’re phobic about, but really, it all is just too damn much trouble to worry about, so you’re just sort of there. Weird, but worth it to be panic-free through situations that normal people don’t even think twice about.
For the people who may comment that you don’t have a phobia yet, I’d focus on that “yet”, and make the suggestion that if one case of turbulence has you quite agitated about the whole idea, then it probably wouldn’t take much more to get you into a full-fledged phobia, which will then be harder to deal with. Better (again, IMO) to deal with the small fear by preventing it from being reinforced in the immediate future by giving you a nice peaceful and calm flight (even if medically enhanced) and then working on dealing more purposefully and consciously with the fear later, if you choose to do so.