Not as bad as you think.
EFA's, DHEA, Vit-E and Vit-D3 etc should not be taken with low fat meals or high fiber foods. So not with oat meal.
Everything else is mostly fair game. Sometimes a certain meal might interfere but so what. That happens with whole foods too.
Multi-vits can be good. Need to choose wisely. Trace elements are important as most enzymes must have certain elements. Some things are needed in such quantities that separate pills are needed such as magnesium and Vit-C. So the amounts of those in a multi-vit are not adequate. Some multi-vits need to span more than one pill, 2, 3 or even 9. Any multi-vit with it short comings is better than nothing at all.
A multi-vit fills in the gaps in your diet that may always be there or periodic gaps.
Speaking of food, your gut bacteria really deliver the goods. Sometimes a good probiotic is needed. Most are me-too useless products, so some homework is needed to find a good one. Contrary to popular belief, getting your gut flora adjusted eating Mexican food does not count.
Do not expect doctors to take care of your health, they really do not know what to do if you do not have a disease. You need to learn to take care of yourself.