I?m worried about water intoxication, please help me calculate the volume of my drinking glass?

Ok, I weight 128 lbs (5 feet tall), and I should drink 8 glasses full of 8ounces of water. (I make frequent trips to the ladies room and I excercise regularly, but I?m very curious)

But, at work, they have paper cups which are not quite a cylinder shape because the bottom diameter is smaller than the top. My main questions are:
1) How much water is in my 1 paper cup?

2) How many paper cups of water should I drink at work to fulfill at least 8ounces?

Here are the measurements of my glass:

The glass height is 4 inches
The bottom diameter is 2 inches
The top diameter is 3 inches
The glass is 2 cm thick.

I fill my water cup to the rim leaving no room. I spend A LOT of time at work, so there are times that I don?t drink water when I come home, and I just take a shower and go to bed.