Hi there,
There are lots of good reasons to be veggie but you really need to get some good advice. I strongly recommend seeing a dietician.
The best foods for iron are green leafy vegetables. Make sure you consume veggies with vit c (eg red capsicum) at the same time to maximise absorption.
Also did you know that tofu is soy? From your post it seemed like you thought they were different things. Soy is fine in boys in normal quantities. You definitely wouldnt use a soy supplement or similar though.
You also need to look into B12 if you are not giving him dairy. A B12 deficiency is very dangerous and generally comes from meat, dairy and egg. For a strict vegetarian you would get it from seaweed, mushrooms, soy milk fortified with B12, marmite and supplements.
Also is your bub bf or ff? If he is bf make sure you are eating properly or taking a supplement. If he is ff he would get most nutrients in that.
As I said, definitely look into a dietician as you need to make sure your bubs diet is balanced.