In my experience milk thistle does not live up to the reputation.
A few possibilities are:
You are sensitive to salicylates. Many or most herbs are high in salicylate.
If this is the case try (and google) failsafe diet.
Dandelion works by stimulating bile flow. Silymarin works as a hepatoprotective. They have different actions.
The extent of the damage/imbalance is very important to know. If your liver is packed with hardened stones then the herbs you are taking are not recommended. Think of a garden hose jam packed with pebbles completely blocking the water from exiting, and dandelion as slightly turning up the water pressure. It's going to make you feel sicker.
For some people, though, this is enough to get them out of a jam.
Moreoever, imo your ayurvedic body type/dosha is paramount to know in navigating through this.
Bitters are not good for vata at all. For pitta and kapha it is the opposite. I find that your sense of taste is a good indicator. If you can't stand the taste of bitters at all it is one indicator of a vata imbalance/constitution.
Vatas tend to do better with higher fats and savory herbs. Whereas pitta will do well with lower fat, raw foods, and bitter herbs.
I would say stop the herbs. Try coriander seed powder, guduchi, and perhaps a little but of turmeric. If you do well on turmeric then increase the dose. The above are are pitta pacifying liver herbs.
If that is a disaster then try warming savory herbs like cooked garlic, cinnamon, cardamom, fenugreek, cumin, star anise, ginger*****, cloves, etc.
High protein/meat diet can be a disaster for pitta.
or coffee enemas
are in order, and a change in diet/lifestyle.
'Other stuff that's supposed to help' ... Healing is not one-sized-fits-all.
There's a good chance you have critters in your liver as well, which will have to be dealt with as you clean out. File away in your head the possibility of liver flukes.
Beets, beet juice, anything beet is a good functional food for the liver, as is lemon juice. Both are geared more toward vata constitution.
All of the rbti people are on some sort of lemon drink long term to help rebuild the liver.
If you have scarring or serious damage then you might want to look into wobenzyme or high enzyme fruits such as pineapple or kiwi. If you are not a vegetarian you might try eating some clean animal liver once a week or so and see if it helps.