It is probably not proper for us to tell you what is ethical for you to do.
Nevertheless, it seems to me that the best approach if you want to reduce your impact on animals as well as to take proper care of your health (far as vitamins go, anyway) is to simply put some effort into having a more balanced diet. But I may easily be missing some significant factors, so you will probably want to seek your nutritionist, doctor or other qualified person face to face.
I would think that iron is easy enough to take, by way of beans, nuts, lentils, soy, pumpkin seeds, quinoa, spinach. Cooking in iron pots is supposed to help considerably, too. It is advisable to lessen you intake of coffee and to attempt to take calcium at different times from the iron, though. Taking Vitamin C helps in the absorption of iron as well, so try to combine iron foods with Vitamin C foods.
Vitamin D deficiency is often strongly linked to a lack of sunlight, so you might want to consider changing that. Food sources include mushrooms (particularly ****ake) and several brands of orange juice and cereals that are treated to have some of it.
However, I would advise you to keep having the medical supervision that you need and taking the nutritional supplements that are recommended for a while at least. Changing your diet might well lead to lessening or even removing completely such a need, but it is best to let your doctor say if it is working and to which degree.