If I'm interpreting your question correctly, you are printing design drafts on the office printer in order to test them out, you have no color management in place in your workflow, and you don't possess a Pantone swatch book so you're thinking of picking Pantone colors in your application that seem to match a given printed color. It's evident that your monitor and your printer interpret colors differently because neither has been calibrated.
For exact color choices, you need to be working with an actual, physical Pantone swatch book. If you plan to go to press using CMYK without solid colors, you'll need a Pantone Bridge swatch book. In your layout program, assign all colors as spot colors using the swatch numbers you choose.
In addition, any experienced designer will strongly advise you to set up a fully color-managed workflow if you plan to do this kind of thing regularly. That means purchasing color calibration equipment such as this for both your monitor and your proofing printer. Even so, you still need actual color swatch books for very exact matching.