I have had a horrible time getting up my calories too so I feel your pain. I have gone from about 1000 a day to 1800 calories pretty much overnight once I found out I was pregnant I had to majorly jack up my carbs too so now I am having 70 -90 carbs a day. I have used nuts quite a bit to help get numbers up and for me they haven't caused one bit of trouble. You can always try them and if they do cause you problems cut down and find the amount that suits you. Some of the ways I use them are
Salads (sunflower seeds are wonderful at replacing that old familiar crunch of croutons), Sauteed asparagus in butter with toasted walnuts and a queeze of lemon are awesome! Ricotta cheese mixed with a little splenda and vanilla and topped with fresh raspberries and chopped pecans or walnuts is delicious. Almonds are plain old wonderful no matter what way you use them. I am particularly fond of the smoked walnuts myself. Almond butter on LC toast if you use that is also a great way to get in some extra calories and fiber. I do used peanut butter occasionally but its usually my last choice when it comes to the fatty nuts. Having a nice cup of tea with some heavy cream is also another painless way to get up those calories and it won't effect your carbs.
Anyways I wish you the best of luck getting up those calories! Also take into consideration that my suggestions aside from the tea are all post induction suggestions.

Jenn