Thanks for the input, I measured the voltage I was getting on the analogue pin itself and it is working like it should, it varies how and when it should, but I still get the constant value of "1023" on the serial monitor.
I also tried making the input ground, and got a constant "0" and then made the input 5 volts and got constant "1023" as well, looking around I found that this was a basic troubleshooting procedure and it looks like in this aspect it's working fine.
As far as joining my grounds I'm only using the 5 volt output and ground from the Arduino so everything's got really only just one ground connection.