Nothing in that data is abnormal. Actually looks fairly similar to my own.
Whatever is causing this, it is most likely not your line, nor your gateway.
It does sound as if your service profile was spontaneously switched. I did have this happen once myself, about 18 months ago. ATT said it shouldn't be possible, but it is, since it did indeed happen.
I would say the best confirmation of whether it is your service profile is what speed you currently getting on a speed test under optimal conditions. If it is ~11.57 Mbps Down/~1.47 Mbps Up, that would match perfectly with a 12 Mbps profile, minus overhead.
Also, you didn't mention if you have any other services with Uverse. If you also have the TV service, and are running more than one HD stream at any given time, your Internet speed will drop accordingly.