After some meditating yesterday I thought I had figured it out,
If Rf=Rg and R1=R2
Vout=Rf/R1 x (V1-V2)
So I changed the resistor values,
Vout = 5V
V1-V2=0.100V (This i wasn't actually sure about but i figured that it'd be something like that)
Which meant that:
5=Rf/R1 x 0.100
5/0.100=Rf/R1
50=Rf/R1
Based on that I chose the new resistor values Rf=4.7K R1=100
4700/100=47 (which is close to 50 so I thought it'd be enough)
Sadly this still isn't enough gain to get any reading on the voltage change, which I find strange but I'm going to try to double it and see if that works.