I'm around 25 weeks along, and I had some pretty bad morning (read: all day) sickness in my first trimester. This is my second pregnancy, and I actually had it worse with the first.
I too fell way off track, since rice and oatmeal went down and stayed down, and I had aversions to many of my normal primal foods: eggs, raw veggies and chicken all repulsed me. It was a problem. But it went away in my second trimester, and I was able to get myself sorted out.
Here's one funny trick that helped me -- a shot of apple cider vinegar. Stopped some pretty bad nausea in its tracks. Might not work for everyone, but if you think you can handle it, it might be worth a try. And I found that having something, anything, in my belly helped keep me from feeling too bad.
You can definitely get back on track. The huge benefit of eating primal during pregnancy is that you'll be ensuring that you're getting a wide range of good stuff from all the nutrient-dense foods. My doctor has always been very impressed with my blood-work. (My answer: "Well, I eat a lot of red meat!") So without getting carried away (eating for two is a fallacy) I wouldn't worry too much about your weight gain. And you probably won't lose the water weight until after you've delivered, to be honest. Retaining water is a pretty common pregnancy symptom. You may just have to make peace with being puffy for the next 30-odd weeks. Sorry.
Personally, I tend to put on a lot of weight at the beginning -- a pound a week for the first 15 weeks -- and then slow right down. To the point that my OB was concerned last time that the baby wasn't growing towards the end. He WAS growing just fine, thank you very much, *I* was just tapping my own fat stores. In light of Mark's recent post on how women store fat, it makes a lot of sense, actually. But also remember that every body is a bit different.
And breastfeeding, if you're planning to do it, really is great for burning through your fat stores later.
Congrats and good luck!