I've Been Taking One 200 MG Bupropion HLC XL In

I've been taking one 200 MG bupropion HLC XL in the am. My doctor upped it to 300 MG at 150 in the am and 150 in the pm. I read online you should take the complete dose of 300 all at once. Not sure what to do. I weigh 125 pounds and wonder if seizures might be more likely with my size and large dosage all at once. My dr. Is out of town and unavailable.