Boy, you have a pretty nice problem
But really, the size of the plant has nothing to do with it. Don't worry, if the plant is flowering, it's because it's ready to do so.
If you are referring to the size of the actual cucumber, it's normal for the cucumber to only be 1 in. long with a flower on the end. It is by the pollination of this flower that the cucumber will be able to grow large.
You cucumbers are actually doing great