Hi Andy,
If you are taking natural vitamin E, a dose of 300 mg (about 450 IU) daily is not high at all and shouldn't bother your stomach. I know thals taking more than double that daily, and their body weight is much lower than yours. I take 400 IU daily right after breakfast and have never had any problem from it. Make sure the vitamin E is natural. It should be D-alpha tocopherol, not DL, which is synthetic and of questionable safety in doses of more than 100 IU daily. The magnesium dose seems a bit high and it should be balanced with calcium, which may also soothe your stomach a bit (most antacids use calcium for this purpose). Your hydroxyurea dose isn't high and is giving excellent results. Are you also taking vitamin D? This is necessary for proper absorption and regulation of calcium and magnesium. Keep in mind that the gastric discomfort may also be related to the hydroxyurea, as this is one side effect of the drug. Eating smaller more frequent meals is one way suggested to lessen this.
I would advise that you be hesitant about changing much of your program. The magnesium can probably be lowered, but you are getting such good results, that it would be hard to argue against continuing. In fact, you respond so well that you would probably also see some results from wheatgrass in some form.