It means it has been only a few years since we last met.

It always has the potential meanings such as the time goes so fast and the things changes a lot. 比如： 几年不见，你孩子都这么大了。 几年不见，你都成大姑娘了。

it's mean only a few years latter. Many times, people use this sentence when they see some old friends, but their friends have changed a lot. 仅仅几年不见， 你就变化这么大啦。( a few years later, you have changed a lot.)

something surprised you since you met somebody a few years ago or found something different.

仅仅几年不见 It has been ONLY a few years since we last met. it's often used to show you're surprised by how fast things change 仅仅几年不见，你都这么高了。 仅仅几年不见，你都大学毕业了。