Slightly anemic, needing to take iron supplement

So I got my 28 weeks labs back, and I passed the glucose test! But I am slightly anemic. And there are way too many varieties of iron pills I am seeing on Amazon. My doctor told me low dose, like sub 35mg a day. But I see chelated, ferrous, mineral, vegan, etc the list goes on. Anyone have an idea on what the best/easiest type to take? I have been having some morning nausea pop back up again now that I’m in the home stretch at 31w5d.

Thanks in advance!