Yes, I'm managing it.

The first thing you probably need to do is get help to work out what's causing your IBS. Don't guess or see a "nutritionist" or whatever. See a proper doctor and dietician who understand the condition. For me, this meant following a low FODMAP diet until I could work out what foods were giving me grief and to what extent. Then armed with that information I was able to work out what exactly I could eat in order to gain without (so much) IBS pain, and I reckon you can to.

As few pointers:

1. Learn how to cook stuff you like and don't be afraid to adapt recipes. There are lots of low FODMAP ideas online now, for instance, if that's your problem.
2. Be prepared. Cook lots of stuff in advance and have food you can eat with you when you travel, at school/work, when your tired and don't want to cook. Don't leave food to chance or at best you'll miss some gains, at worst you'll be ill.
3. Learn to be good with money. Gaining can be expensive but when lots of common gaining foods are off limits (e.g. oats, bread, cottage cheese, yogurt, pulses, many fruits and veg), your food bill can rack up.
4. Things will probably take longer. You're body will take longer to get used to more food so you have to go slowly and stick with it.
5. You'll still spend a lot of time on the toilet. Hopefully this will be because you're eating a lot more food rather than because diarrhoea strikes again. (However, flushable wet wipes are amazing.)
6. You and your body adapt and change. I can now eat stuff I could never imagine eating years ago as my body has got better at handling IBS. Other things I still can't handle but I've learnt to like foods without so much onion and garlic, for example.
7. IBS is affected by more than just food. Better sleep, decent exercise, good relationships and less stress all contribute to better digestion.

I love food but food doesn't really love me. However that hasn't stopped me enjoying food or from seeing the positive effects of gaining wait in my life. I feel a lot more in control of my body and a lot healthier for it and I'm sure you can to.