I believe you can safely flush during pregnanacy, based on all stories from women who has done Liver Flushes (no one reported any problem), based on the fact that Epsom Salt is a standard tretment for pregnant women and based on the experience of my wife, who is also pregnant and flushing with no side efects, only 100s of positive efects.
The stones you got during your first Liver Flush may or may not be from your gallbladder (most likely from your liver), but getting those stones out can certainly improve your helth and after several flushes, also all stones from your gallbladder will find the way out.
Considering your diagnoses, I would do one flush about every 3-4 weeks. (Listen to your body. If you feel good, you can flush whenever you want, if you feel that flushes take your energy, you can flush only when you feel it is the right time for you.)
Considering that you are prgnant, you should eliminate all processed foods from your diet, and avoid eating foods from restaurants, eat only foods that you prepared at your kitchen, from the fresh, safe and natural ingredients.
Eliminate all refined foods from your diet, especially Sugar and other concentrated sweeteners, and refined salt, refined oils, margarine, deep fried foods...
Use only 1 or 2 tbsp of Epsom Salt instead of 4 tbsp, but use the same amount of water. Not because Epsom Salt is toxic, [dissolved epsom salt is actually routinly given to prgnant women by doctors, even inrovenously when doses are many times higher then when you take it orally], but because you don't want to provocate too strong diarrhea when you are prgnant.
You should also do water enema in the morning or during th day the same day you are clensing, and you can take an enema the morning after the flush, to insure your bowel is clean from the bile dumped by your liver.
Any time during pregnancy you have any digestive problems, (food poisoning or eating something that mekes you feel bad), you can take 1 teaspoon of epsom salt (also called Magnesium Sulfat Heptahydrate) with a glass of water, and that will most likely solve all your problems.
But, always be aware that food you eat is more important then "band aid" in the form of epsom salt. You should ot rely on epsom salt daily!
Enema is also perfectly safe during pregnancy, as long as you don't overdo. Constipation is very common during prgnancy!
Please read Prgnancy forum and read also the same question in FAQ forum, and you will find a lot of good answers and suggestions.
By reading other women experiences, you will learn a lot ...