I'm a little paranoid as well. Comes with being 1st time moms.
When I discussed switching from formula to milk with DS's ped, I asked if I should add a multivitamin and he didn't seem concerned. I do read the labels on the foods we get specifically for DS, and try to make sure at least some are iron-fortified.
Good nutritional iron sources include: beans, eggs, spinach, broccoli, red meat (beef, pork), fish, tofu, fortified cereals (check the label). Iron is also better absorbed if it's combined with vitamin C... so broccoli is an especially good source, as are lots of other fruits & vegetables, and diluted juice. I read somewhere that toddlers need 7-10mg iron/day.
Also, more than 24oz milk per day can inhibit iron absorption.
here's a good overall "toddler nutrition" link:
http://www.wholesometoddlerfood.com/toddlercalcium.htmFor omega 3 & 6 (DHA/ARA), good sources are nuts (esp walnuts), seeds, fatty fish (salmon, sardines), unrefined whole grains and flax seed.
We try to have salmon weekly, use lots of whole-grain foods and add ground flax seed to various foods (esp oatmeal & similar).
Really, except for the higher iron, this is how we try to eat, as well.
(I'll probably still start a multivitamin before he's 2.)