Actually, the USRDA amount is the MINIMUM that you need to keep your body from disease. It is not the amount that you need for best nutrition. Typically, it is far lower than the amount you need to feel your best. For example, B12 RDA is 2.4 mcg (on government website last I checked) yet for myself, I need 1000 mcg minimum.
I would see a doctor, have your blood levels tested for all vitamins, then find a supplement or two that meets your needs.
Oh, and to the last post about vitamin A, you can safely take 25000-35000. Levels ABOVE 100,000 IU are considered toxic...no where near the RDA of 700 IU.
I would also recommend reading The Optimum Nutrition Bible. I was hesitant to read it at first, but I found it full of information!