If I have very low iron levels in my blood history of gastric bypass...and supplements aren't helping lunch, what would he the next best step?

Low iron levels. Your clinician needs to review your entire record, history, and complete an examination on you. This is a tricky situation. By your question, you are associating the bypass surgery with the iron deficiency. While you may be correct, there are other causes for iron deficiency, as with a myriad of colon problems (colon cancer, i.e.) that must be considered. Seek help as soon as possible.
Common problem. After gastric resection, due to by passing duodenum iron is not absorbed, will have low serum feritin levels, especially bigger problem in young females, need to take more oral iron, iron containg foods like liver, meats, oysters etc. Vit c found to help iron absorption, must take vitamin c with ferrous sulfate, rarely need parental adminstration of iron in severe cases.
You need. A full hematological and GI workup to determine the cause of your iron deficiency anemia.