Eating (un)healthfully

So, according to What to Expect When You're Expecting, an excellent diet during pregnancy leads to excellent health of the baby. Unfortunately, the book says, most pregnant women simply have a medium-good to low-excellent diet, leading to medium health for the baby. I honestly do want to give my baby the best possible start in life, but eating healthy is SO HARD when you love the following things so much:

1. Pizza!
2. Peanut butter (in large amounts and frequently, not these 2tsp servings)
3. Taco Bell (I had stayed away from this for so long, but the other day, in a moment of near-starvation, I headed for the border, and my taste for the Bell is ba-aack!)
4. Eating in general.

I enjoy eating, okay? I'm not a glutton, and my portion sizes are good, but I certainly don't have an excellent diet, especially on weekends. Also, the whole varied diet thing? What to Expect's Best Odds Diet gives you twelve food groups to work into your day, from green leafy and yellow fruits to protein and iron. Geez! This means every single thing I eat needs to fit into one of these categories, and not a category I've already met my quota in for the day!

And then I hear some people say, "Who cares? You're supposed to gain weight; eat what you want!" "Those vitamins will take care of everything you need!" (That last one might have been a voice inside my head.)

For now, I'm trying my best to steer clear of fast food and desserts and control my portions. On weekends though, just about anything goes. Any tips from healthy eaters and/or mommies on getting all the nutrients my baby needs?