Yes this can be anxiety and if you have had all the tests then IMHO I would like to suggest you see your physician and ask for something to help with the anxiety. Your going on a trip, a long flight and your bound to be feeling anxious even if your looking forward to going.
Talk to your Dr. and tell him about the anxiety and the possible need for medication. You might try this: Relaxation exercises are techniques to relax muscles and relieve tension by using controlled breathing and muscle flexing. They usually involve sitting down in a comfortable chair, closing your eyes and systematically tensing and relaxing different muscle groups in your body, usually starting with the legs and feet. Take care and keep posting.Kitt