Help with function regarding sum and filters

Hi,

I am currently working on a project and need some help trying to solve an issue. 

I am trying to build a measure that allows me to sum weights after filtering down based on the type of item it is , also select a month it was purchased on a slicer, and then multiply that number by a selected value on a parameter. 

So far I have came along way, but would like to be able to adjust the parameter slicer by each month without having the other months become messed up when I change the value it is being multiplied by on the parameter slicer.

To sum it all up, I would like to be able to find a total currency value for the whole year by adjusting the price per pound by month using a measure without having the other month amounts being messed up.