How To Increase Hemoglobin In A Person Allergic To Iron?

Hi...my hemoglobin is 9.8 in 5th week of my pregnancy. I am allergic to iron which means I get dehydrated as soon as I eat iron rich diet , so find it difficult to eat iron supplements. Even if I eat a full bunch of spinach a day , the next day I am all dehydrated & on bed. What should I do to increase iron in my body?