It's important to figure out WHY your iron got low. Typical causes include 1) heavy menses, 2) GI blood loss due to ulcers, polyps or other pathology, 3) celiac disease or gluten or dairy sensitivity. Given your history of IBS I'd suspect # 3.
Iron glycinate is the least constipating iron; time release is second best. Taking vitamin C or OJ with your iron improves absorption. Liver is the best source of dietary iron; any kind of beef is second.
