The decision of taking or not taking the thyroid pills is best decided by your treating endocrinologist after an evaluation. Bile does not have anything to do with gastritis. Limiting fat intake can limit bile secretion; though with GB removed fat is best limited to prevent malsorption despite having no effect on bile secretion. For gastritis/ lowering acid production, it is advised to take the medications as suggested by your treating doctor. Also taking small frequent meals and avoiding hot/ spicy/ smoked would be suggested. I would suggest discussing the situation and the suggested management plan in detail with your treating doctor.
Hope this is helpful.
Looney, although the term bile reflux gastritis is still controversial and it has not specifically implicated in 'gastritis' it is known to numbers of individuals who experience it and to doctors who are seeing it first-hand more and more frequently.
If the surface of your stomach has been examined 'microscopically' and the erosion and presence of a 'tile-like' pattern (I believe that's how it's being described, but I could be wrong) is found, it is possible the erosion that is seen may be due to bile.
Many foods result in bile production, so it's best to stick to a low fat diet overall. Some find that vomiting of bile can be lessened by following a gluten-free diet IF they have gluten sensitivity in any form.
Bile issues are more common unfortunately in those who have had their gallbladder removed. You may want to consider working with a GI person who specializes in working with those who have issues that fall into the category considered 'post-cholecystectomy syndrome'.