I can symapthize! I always wonder at some point if I will be ready...even after I did really well at Jr Nats, I was nervous if I'd be ready for Nationals! And I was already dieted down!
My advice is this....you have a LONG time to prepare, plenty of time to be ready. Now is the time to pick you plan of attack (diet, training) and get going. Stick to it and don't waver no matter who wants to give you advice. Stay the course and trust your program...also, book everything and get your suits (suits take time to order and get anyway) because then you are less likely to back out once you have committed time and money!
And I really think that even if you don't place where you'd like, you will still love the experience. You will make changes you never dreamed possible and you will have a sense of real accomplishment. I never did all that well in my first shows but I still had a ball and it set me up for future success. And honestly, even going into Nationals where I got my pro card, I STILL did not expect to win, nor would I have been upset if I didn't. Competing for me is a journey and an experience I relish...title and trophies don't mean as much as memories to me

So the fact that I was so well rewarded turned out to be icing on the cake---I compete for many reasons other than just placings
Good luck and stay strong!