When mine finally flared, I had actually not been eating anything especially high fat. Though the half-glass of bad red wine might conceivably have contributed - that’s a WAG based on liver / gallbladder being sorta connected, and may be purely coincidental.
The tech who did my ultrasound (to confirm the bag o’ rocks) said she’d been involved with a study that showed that fat in the diet does NOT contribute to an immediate flareup, but that’s the only time I heard that particular theory, and conventional wisdom says that it does for reasons already mentioned.
All that said: In addition to the low-fat requirement, I had a very high blood sugar reading during that, certainly caused by the flareup. I’m not sure whether it was directly caused (as in, gallstone blocking a duct from the pancreas, or bile backup irritating the pancreas - my liver was definitely involved), or just a blood sugar spike due to being so ill for several days. My reading (fasting) was 154. 2 weeks later it was 107 - still higher than desirable but in line with the fact that I’m a tubbo.
So anyway, for about 6 weeks before I could get that sucker yanked, I was doing low fat AND low sugar. Short of living on plain chicken breasts and steamed broccoli, there’s no way to avoid ALL carbs if you need to avoid fat also, so I took the stance of concentrating on complex carbs and small quantities of fat (if any). For example Christmas dinner was roast chicken, a roll, a very small sliver of butter, and about 1/4 of a stuffed potato.
Beef barley soup (made with ultra-low-fat ground beef and a higher ratio of veggies) was a favorite, as was a barley/lentil soup from Epicurious (look for barley lentil soup with swiss chard - I usually reduce the chard, a LOT).
I’ve never heard of carbs being an issue with gallbladder problems, though you want to avoid going overboard on sweets obviously simply because they’re not good for you. I personally tried minimizing even fruit, though I didn’t get too paranoid about it.
Good luck - and if you haven’t already, try scheduling that appointment for January 2 to get things rolling ASAP.
BTW, I hear ya on the out of pocket thing. The year of the gallbladder, pretty much everything else was also falling apart. Between the surgery, and some apparent stomach problems which turned out to be a drug side effect but got me in for additional testing including a colonoscopy, I hit my out of pocket limit by July (simultaneously wiping out both my and my husband’s flex spending accounts)… so the rest of the year was free! This turned out to be helpful in that I got several other things taken care of later that year.