how do I know if I need supplements?

You actually have more than 1 question here but let me start with the supplement question. If you eat a varied diet with many different colored fruits and vegetables, with whole grains and beans as the basis of your vegetarian diet, with the occasional egg, you may be getting what you need. If you don't eat any animal products, you may need a vitamin B 12 supplement. Taking a standard multivitamin might be fine for you although choosing the best for you foods is really the place to start.

Now, about your "health" problems, I can assure you that acid reflux, headaches and tiredness are not part of what I consider the best health. And they often are related to what you are eating.

You can see if eating a cleaner diet without wheat, soy or dairy might make you feel better. Try it for a few weeks and see how you feel. It doesn't need to be "fancy" and it is based on whole foods. If you don't give it a try, then you won't know.

I wouldn't want to be faced with your non-health issues. That would make me tired.

A vegetarian diet is usually lacking in Vitamin B12. You could take supplements for that. But if you feel you are not getting enough protein in your diet I think Royal Greens Ultra might perfectly suit your nutrition needs. It has got over 50 natural whole food sources and is purely vegan. It contains the best protein source there is—spirulina and chlorella— which has more protein content than even meat, and in a more easily digestible form. Fiber, enzymes and probacteria make it a complete food supplement. And yes, strangely enough, it does taste good!