Family history of glaucoma is a strong risk factor for developing the same problem, but, still, increased pressure within the eye is the major risk factor.
Gradual loss of vision, pain in or behind the eye ball, headache and sensitivity to pressure, could be symptoms of glaucoma.
I think you should get a new glasses prescription (you are getting headaches, and tired, weepy, painful eyes as you strain them and surrounding muscles to see better).
Regular check ups are important for people that are wearing glasses and the ones with family history of vision problems.
Best wishes!
Marija