I was trained in hypnosis / hypnotherapy at the University of Washington
Hypnosis can be very useful but if you haven't had any previous experience with it you may not want to try it out on diving.
The benefit of hypnosis is that it allows you to focus on a subject or issue without the prejudicial baggage that surrounds the issue and that we all carry around with us.
I have been diving for more years than I usually admit to being in age. I have dove with litterally hundreds of dive buddies and my experience as a scuba instructor tells me that for the most part you need to hone your skills by diving, diving, diving, under the guidance of someone whose skills are significantly more advanced, A divemaster or instructor etc. Make the point of your dives to become better and the self confidence will follow once you proove to yourself that you can do it.
I would also suggest that you really try to establish what it is that bothers you about diving. Is it the Distance/depth of the water or the fact that you can't breath for that distance/depth in an out of air situation? Is it the level of understanding that you have in regard to diving?
Here is an excercise that usually works for divers I have encountered with similar problems in the past is to take a long tape measure. Mark out 130 feet on a straight horizontal line (the maximum sport diving depth). Set a chair or other type of pole, standard etc. on the far mark. Look at how far away it is. You will suprise yourself how short a distance this seems on a horizontal plane. I gurartee you it is no farther away on a vertical plane. Now take a few relaxing breaths then hold your breath and run the distance. See how easily you can cover that distance. After that take a few more relaxing breaths, Hold your breath and walk the distance. Most people can still cover the distance without breathing.
If the problem has more to do with the increasing physiological dangers of diving, again I would say that you need to Practice, Practice, Practice and make sure that you really understand the information in your dive manual. Take additional classes, especially classes that deal with specific fears you may have.
Unlike basketball where anyone can walk out on a court and toss a ball at the hoop then go home without injury having never really understood the sport, Diving is a sport that you really need to understand. Study all the information in your dive manual and skills practice is a must. Once you can clear your mask in 6 feet of water easily you should be able to clear it in 100 feet of water easily...
See you in the Sea