multiplication of two 14bits number

The problem isn't particularly related to FPGA arithmetic and signal processing. I suggest to clarify the intended behaviour by utilizing pencil, paper and a pocket calculator.

P:S.: For the more technical "how can I do", you can either decide for the "big" solution IEEE fixed point package, perform all saturation, truncation and rounding inline in your code (rather inconvenient, I think) or have one or more functions wrapping it.