I found I was better able to control it by strictly limiting my fat intake - but as it progressed over a few months it got worse and in the end I'm not sure what was triggering it.

Things that were good:
small portions of chicken BREAST or heart-smart beef steak - there are lots of 98% fat free marinades you can buy - done in a non-stick pan with NO oil
Plenty of pasta, steamed/dry baked jacket potatoes, sweet potato, rice, etc...just prepare them yourself and don't add any butter
The Weight Watchers ready meals are handy - their pizzas are a life saver 5-6 grams of fat and quite tasty - just read the panel on the box and work out (by experimenting) how many grams of fat you can have in one sitting without an attack
I found I had to eat an extra snack each night because I was always hungry - something like low-fat yoghurt or custard with fruit and muesli/cereal
I would use tiny quantities of extra light products like sour cream, cream cheese, grated cheese -but only when I weighed it so I knew I wasn't having more than 3 -5 grams of fat in the meal. If you have digital scales you can actually weigh the stuff as you add it to the sandwich, for eg.
Pre-packaged low-fat lunch meats are a good source of protein with not much fat. Same for low-fat bacon.
My DH found a nearly fat-free muffin recipe (used applesauce and a single egg to bind it) which were nice for a change. You can also make pancakes in a non-stick pan but don't add butter or anything when you're eating it
Small cans of 98% fat free tuna - they will do for a pasta sauce when the rest of the family is having bolognaise.
Low fat tzatziki and hummous in moderation are good
You can get these flavoured fish fillets that you steam in the microwave...yummy.
Air popped pop corn, rice crackers (read the packet -some have more fat than others!) and almond bread are good snacks.
There are these chips called sultry sally which don't have much fat in them - good for variety
Plenty of fruit, dried fruit
Bread, pretzels, crumpets, fruit loaf, english muffins, and some bagels are good. Just read the packet and aim for 3-5 grams of fat per meal. Just watch out because some breads have more oil in them than others. I sometimes used a small scraping of ultra-light margarine which seemed to be ok.
Eating out - McDonald's LEAN beef burger with NO CHEESE and no fries - ok. The subway less than 6grams of fat sandwiches - no cheese - ok. Sushi rolls - good but choose fillings like seaweed salad, mushrooms, cooked tuna, etc and not the fried fillings.
Shout yourself some treats like boost juice (some of their smoothies are lower fat than others, they have a card with the values on it), Wendy's chocollo icecream, sorbet, nestle "diet" desserts (dairy cabinet), etc. Add some fruit and they can be quite satisfying.
For breakfast, porridge or low-fat muesli is really satisfying and if you have a bigger serve it will help with some of the calories you are missing out on for the rest of the day.
I also snacked a lot on naughty things like chico babies (chocolatey taste) and marshmallows.

It is a bit of a bother when you have to eat like this for a while - but it's worth it - the less fat you eat, the less aggravated your gallbladder will be, the fewer attacks you will have. If you're finding your changed diet is reducing your supply, then see a dietician as they will have some good tips on how to boost your calorie intake without adding fat (specifically by adding denser carbohydrates and more protein.

BTW - some ppl can eat most anything that's not deep fried without having attacks. I wasn't one of them. You will learn how much you can get away with. See your dr about how to best manage when you have an attack coming on. I found drinking a large glass of water when it started helped (esp once I started going to the ER for morphine - meant they could find my veins a bit better) - as did sitting upright - or even sleeping upright overnight in my recliner armchair.

I really think you can do this. You can get through this. If your symptoms escalate, keep going back to your dr/going to the ER. It only takes a few attacks right on top of each other to get you escalated onto a more urgent surgery list.