Congratulations! Is this your first baby?
Just remember that you're not eating for two. You're eating for one and a grain of rice.
A the end you're eating for one and roughly 8 lbs. It only takes an extra 200-300 calories per day (no extra in the first trimester, actually) to build a baby. Just keep up your healthy eating and exercising habits and you'll be fine!
"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly..."