I've been eating a lot a sugar for a few weeks an now I am having hot flashes and and blurred vision I am a teenager and take birth control.

Also: Get Eye Exam. Blurred vision can be a result of retinal vein occlusions that are increased in patients on oral Estrogens or birth control pills. I would recommend a dilated retinal examination to evaluate for possibility of other causes of the blurring. This should be combined with glycohemoglobin level, fasting blood glucose and also lipid panel and liver function tests.
Check your bloosugar. You should stop eating too much sugar and get your blood tested for blood sugar to rule out diabetes.And see an eye doctor to have your eyes tested.