Iron from vegetables is poorly absorbed, but taking vitamin C with it massively improves absorption. If you’re supplementing vitamin C, try taking it with some greens.
Phytic acid is a chelator and may prevent you from absorbing minerals like iron and magnesium. So go easy on the oat/rice bran (there are other reasons to do this).
Iron can be dangerous in excess, so I’d just stick to food sources if you can, and see how you feel. One rough way of spotting anaemia is by pulling the skin below your eyeball down slightly. It should be lined with red underneath, but tends to be normal skin colour in anaemic people.