Hey

This is all good news and plans, I am sure things will work out great for you.
I've been working with pre and postnatal training and nutrition for about 5 years now, and I have seen a lot of women enjoy an ongoing exercise program + great prenatal modification and easy delivery and recovery.
Preparing to get pregnant is key, since you would ideally be at a weight that will allow you to gain some pregnancy weight and at a fitness level where you will have a painless pregnancy once you conceive.
There is no reason to get freaked out about having a child, it will NOT destroy your efforts in the least.
Most books on pregnancy and post pregnancy fitness are written for the non fit women and you would probably find the ones available pretty boring and not very useful. Tupler's books (Maternal Fitness and Lose Your Mommy Tummy) are a good read to get a grasp on abdominal control. I find
this book great, but it still won't give you what you need in terms of real exercise.
This is how it usually goes in previous clients like you:
1. Focus on weight loss and a well balanced strength training program that is total body and very focused on lower back / hip balance and upper back strength and abdominal / static strength; get adequate nutrients (e.g. folic acid), limit toxins
2. Once pregnant, get cleared by doctor and lower intesity while keeping to strength program; include pelvic floor exercises, up aerobic activity; stop all high impact or dangerous activities
3. End of 3rd month and later: discontinue all activity on your back, keep postural training, keep moderate intensity with weights, focus on stabilization, moderate aerobic activity
4. Monitor how you feel for months after 7 to decide how to modify rest intervals and weights, switch to multiple shorter workouts, rather than 1 long session
There is no reason why you shouldn't have a great carefree pregnancy, enjoying little weight gain and adequate physical activity. It will all depend on your health at the time, so for now, focus on being healthy and happy and decreasing your weight
Good luck
Galya