Is this like childbirth?

[BLT]

Ditto to Beeger's points.

I have observed many in-water training sessions and you can rest assured that your experience is not unique. Its important to know others have went through the same problem. You also did one of the toughest things in diving - to stop instead of continuing when you know something is not right.  There can be a great 'assumed' peer pressure in diving.

Ask your instructor for tips on how to practice the part that is giving you troubles.

It is incredibly common for the the upcoming pressure of a trip to complicate matters. Try and relax. My favorite diving phrase is "Take your time, there's no rush". If you feel rushed, let your instructor know and work something out together.

Once you make it through training and hit that nice warm clear water you'll be hooked....