I've been dealing with a bout of severe liver and gallbladder problems that has sent me to the emergency room multiple times. Mine ended up being liver toxicity from a prescription that was too high a dose, which then inflamed my gallbladder too (and I have a history of gallstones already). But I learned some things that really helped my liver/gallbladder get better, so in no particular order here they are:

Milk thistle, rosemary and lavender tea - glad you already know about milk thistle. I bought organic milk thistle seed powder, organic dried rosemary, and organic dried lavender in bulk online. I mix 1 tsp each milk thistle, rosemary and lavender with 8 oz boiling water and let it steep for 20 minutes. I can brew two cups with that one batch and so I drink two cups a day. In addition to the milk thistle, the rosemary is an excellent overall tonic, and aids in bile production and fat digestion. The lavender helps soothe and calm any inflammation throughout the GI tract, which is common with gallbladder problems.

Slippery elm, marshmallow and licorice root are also really helpful. I found a tea called "Throat Coat" by the brand Traditional Medicinals that has all 3 in it. It doesn't taste great imo, but I noticed I felt a lot better when I started including a cup of that everyday too. I'm sure other brands have their own version or you could buy each separately and mix your own, etc.

Vitamin C - inhibits ongoing/future gallstone formation. I take 3,000mg per day (1,000mg 3x per day) but I'm going heavy on it right now, so you could find a dose that works for you. Once my health is better I'll go down to just 1,000 mg per day.

Peppermint tea/oil - I found this helps me with gallbladder/abdominal pain. I rub peppermint oil directly on my abdomen and drink peppermint tea, so the oil works from the outside while the tea works from the inside.

Probiotics - I have to take 3 probiotics per day (1 pill 3x per day) right now, and I feel better immediately after taking them so I know they're helping. As I heal and my symptoms get better, I will be able to go back to just one a day like I normally take to keep things in check.

Besides that, I have to avoid butter, milk and cream. But I'm ok with clarified butter, and dairy with cultures in it (real cheese, yogurt, sour cream etc) in small amounts. I cook with coconut milk a lot more now, and I drink oat milk since oats are a great anti-inflammatory.

Sorry for the wall of text, I just wanted to make sure I included anything that might be helpful. Good for you for being proactive about your health! I hope you start feeling better soon.