Is there any way to be sure i don't have glaucoma, before i even go to the eye doc?

You can't: There are many factors that lead to a diagnosis of glaucoma. Often times, the diagnosis is not black and white, but a grey area. This means that the doctor must consider all your risk factors along with findings on examination to determine whether you have it. Family history and coincident disease are factors that could increase risk.

You don't: You are going to an eye doctor - hopefully an ophthalmologist - to detect this condition if present since it usually causes no symptoms in its early course. Your eye doctor will also determine other aspects of your eye health and need for eyeglasses.