I don't have much to add regarding the parasite/toxin issues etc.
However, since you are breast-feeding and since you are worried about your baby's development I really feel compelled to ask if you are taking a good DHA/DPA supplement?
This is absolutely critical for your health and for the baby's health. This is the number one nutrient that babies need to create nerve tissue and brain matter. Google "breast milk + DHA" or "DHA + early brain development" or anything along those lines