glad to hear you're doing well at the mo. and I can sympathise with the weight loss problem.
The problems are added to of course because of our limited diet... so much loverly grub which is a big no-no ... have you managed to sort what foods you can eat and what makes you poorly?
I know there are lots of supplement and 'build up' type drinks which are high nutrition/low residue (e.g. Ensure, Ensure Plus, Fortisip, Fresubin) most of these are VERY MUCH an acquired taste, but do not be tempted to try the sports type drinks, these do not have the correct balance of nutrients we as Crohnies need.
The only other way really is to go for the foods with the highest calorie intake (e.g. lots of starchy foods, rice, potatoes, pasta, bananas, peanut butter (smooth only, NOT the crunchy) avocados) If you like, and can tolerate dairy foods then go for the highest fat content when you choose your yoghurts, milk, cream, cheese, etc.
I'm just 5feet 2inches tall and find it a constant battle to maintain my weight, the slightest little flare and I go right back to square one... I've been bugged all my life with being a skinny little waif. I've tried lots of different ways to put weight on ... and ..... 'SKIRTS' !!!! ooooooh nooooooo. not for me either. jeans and sloppy jumpers all the way for me.
Hopefully some of the others here might be able to give you a few more pointers.
Hugs for now