Hi Alex,
According to this video from Fermilabs' the size of the CMB (or the whole Universe) was 42 Million light years in radius and it took 13.7 Billion light years to get here.
You have probably seen it before but here is the link anyway.
The video also explains other questions that have you (and me) puzzled.
https://www.youtube.com/watch?v=vIJTwYOZrGU