So is 9mmhg a normal intraocular pressure for a glaucoma patient?

Terrific: The goal of treatment in glaucoma is to get the pressure to a level lower than that which will cause eye damage. In almost all cases, achieving a pressure level of 9 would be considered terrific and vision saving. Normal is a range but with the same issue - preserving vision.

Perhaps: Your IOP seems quite acceptable as long as your treating Eye MD has determined where your target range of IOP should be to protect your optic nerve from progressive damage. The IOP has to be calibrated according to your corneal thickness measurement. For thin corneas, your measured IOP would seem low, but the calibrated would be higher. Your Eye MD is aware of this.

No: Most but not all glaucoma patients develop glaucoma due to a pressure greater than 21. A target pressure of 9 in a glaucoma patient is difficult to achieve even with medication or surgery. However, it is the goal to achieve in a patient with advanced glaucoma.