Need ideas on how to gain weight

So I'm about 112 or so and I'm wanting to reach my goal of 125 is there any ways I can out on good weight, I've been going to the gym and eat 2 to 3 times a day but seem to stay at the same weight most of the time I just have no appetite which sucks. Anything that helped any of you ladies gain weight? I also have IBS so I'm sure that's one reason I don't have much of an appetite.