at 24 weeks i had gained 8-9 lbs. i was worried, and the docs-oh lordy, forget about it. they were trying to shove as many cals down my throat as they could.
it wasn't that i wasn't absorbing my food-i wasn't eating. i had no apetite and if i forced it i just threw up. i carried high and the baby pushed on my stomach way too much to want to eat.
i knew after i had her that my apetite would return and id be fine-i never had trouble before w weight.
the docs were worried my weight troubles would stay but i knew things would be ok. perfectly healthy women can gain only 15 lbs w pregs! my mom was told to only gain 15-20 lbs in her day.
the babies will take from your nutrition so dont worry about them. instead of focusing too much on cals, which can drive u crazy and stress u out sooo much-i'd focus on the quality of your food. get in as much protein from whatever source you prefer-cheese, dairy, chicken, nuts, anything...for a preg woman they reccomend 80-100 grams a day-for twins I'd add on maybe 30-40 more grams at least.
with one protein shake in the morning made with yogurt, protein powder, fruit and milk you can get 25+ grams in. add a piece of whole grain toast with cream cheese and in you can squeeze in 3 pieces of bacon-thats another 12 grams or so.
lunch- a salad with chicken on top (panera has great ones), and glass of milk-another 25 grams....keep going and you'll see it is fairly easy to get the protein in.
when i was preg-eating 3000 cals a day-I didn't gain a lb myself-the baby got it all. and believe it or not, i lost all my weight within a week of delivering. i was 127 pre preg and 5 days after she was born i was 127! my total weight gain at 40 weeks of preg was 17 lbs. the baby was 8 lbs. my appetite is fine and weight is fine. i am 125-i think bfeeding has helped me loose a few. i'm only 5'3 so i can afford to lose a few lbs, its ok.
please dont stress about it! get yourself on a good diet. don't worry about what they say. (unless of course you start losing tons of weight) give yourself good nutrition, focus on that. stress can prevent u from gaining weight too.
why are you concerned about not carrying full term? (if u dont mind me asking)