weight gain question

Killer Tomato

I know you are supposed to put on 35 pounds by the end of a pregnancy...I am a little freaked out by this. (Partly by the idea of weighing 35lbs more, but mostly with the logistics of gaining that much.) I have always been on the thin side, am a vegetarian, and find it difficult to eat huge amounts of healthy calories. I know it is not a huge issue in first tri (which is good, as I am eating less than optimally with the nausea,) but will I just naturally gain the weight later on? It feels like my stomach already gets full quicker...won't it get harder and harder to fit food in there as baby grows and squishes everything? Will I get hungrier and magically be able to eat millions of calories? If I end up losing weight b/c of m/s during 1st tri, will I need to eat even more to make up for it? If I can't manage to gain 35lbs, what will happen? Am I freaking out for no reason?

I know how to eat well as a vegetarian and I have plenty of nuts/legumes/healthy fats and whatnot in my diet, but I just don't know how I am going to eat 2400 calories a day by 3rd tri, especially if I am trying to avoid junk. (This is assuming the online nutritional needs calculator is accurate in its assessment of my requirements.)