Will a lower dose of the combined pill mean i'm not as protected? lower dose because of bad nausea.

You are protected: You still get the same protection at lower doses, unless you are extremely overweight, then it could potentially be lower. The only issue with the lower dose is you could have more breakthrough bleeding, especially if you miss a dose. But you will still be protected.

Yes: Most studies show that the failure rate for oral contraceptives (average dose ethinyl estradiol 30 mcg to 35 mcg) is about 1& to 3%. The same studies show that the failure rate for the "low dose oral contraceptives (10 mcg - 20 mcg of ethinyl estradiol) is closer to 3% to 5%. To a great extent the failure rate is directly related to noncompliance with the daily dosing required for perfect use.