I suck at breeding mice?

[Rhasputin]

Keep in mind you could also of gotten mice that were inbred for generations. When this happens they will not breed and just develop tumors and or die.

This is 100% false. Mice that are inbred and selected properly, are the best mice available. In the show arena, if your mice are NOT inbred, they generally do not do well in the arena, because you cannot improve an animal without inbreeding. Outcrossing, or bad selection of stock, is what causes problems, NOT inbreeding.