Xfinity WiFi Router > AirPort Time Capsule....help??

I just upgraded my home internet and Xfinity sent me a new modem. It turned out to be a modem/router. After installing it, I set it up exactly how my previous router was so that it cooperated with my AirPort Time Capsule (phone line & cable > Xfinity router/modem > Airport Time Capsule (plugged into the first Ethernet port)). At first, I was getting an internet signal from my AirPort network even though it was blinking orange. AirPort Utility then popped up and told me I needed to switch it to "bridge mode" (I think that's what it was) so I did. I got a soild green light after that.

So now I have two WiFi networks broadcasting in my house...the Xfinity modem/router is putting out its own network, and then my AirPort Time Capsule is putting out another, which is the same original network that I had always used.

I feel like this is somehow not the most efficient way to set this up. I also want to make sure I'm getting the fastest signal possible and it isn't being cut in half because of the two networks or something like that...I know I could just get rid of the AirPort Time Capsule altogether and connect to the Xfinity modem, but I want to keep the AirPort to access files saved on it, use it for Time Machine, etc.

Any help? I'm thinking that I'm missing a step somewhere...