It is mathematically possible, but you have to understand the maths. Even if you do understand the maths, it's difficult to get your head round. It's the space-time manifold that's expanding and the relative expansion is not limited to the speed of light. Weirdness ensues, for example non-conservation of energy.
No-one knows how big the universe actually is, but measurements of its curvature seem to imply that it must be much bigger than its observable size.
It might be infinite, or it might be finite but closed and not have an edge at all.