Why has the cosmic microwave background radiation not already left the universe?

Sooo. As I understand it, the cosmic microwave background radiation is the remnants of the light that was created several hundred thousand years after the big bang. If light is the fastest thing in the universe, surely all that light would have traveled beyond the edge of the universe by now? There wouldn't... show more Sooo. As I understand it, the cosmic microwave background radiation is the remnants of the light that was created several hundred thousand years after the big bang. If light is the fastest thing in the universe, surely all that light would have traveled beyond the edge of the universe by now? There wouldn't be any left. Someone pointed out to me that this is because the universe is curved, like the skin of a balloon - is that true? If this is the case then the light that we see, must have gone around that skin several times by now. Not only that, but the light from our galaxy in it's early stages must also have traveled around the universe by now, so is it possible that one (or more) of the galaxies that we see in the sky is in fact our own galaxy? What have I got wrong? Thanks!
Update: Oh hang on. I just saw some more of a documentary (everything and nothing, very good btw.) and the guy explains that because the universe is expanding the light of the CMB hasn't had time to leave the universe yet. WTF? Surely that would mean that the universe must be expanding at close to half the speed of light!? show more Oh hang on. I just saw some more of a documentary (everything and nothing, very good btw.) and the guy explains that because the universe is expanding the light of the CMB hasn't had time to leave the universe yet. WTF? Surely that would mean that the universe must be expanding at close to half the speed of light!?
Update 2: @Zaghawa - But I thought the speed of light was the fastest anything can go? How could the universe be expanding faster than the speed of light?
Update 3: @blobrana. So what your saying is that the universe started off expanding incredibly quickly, slowed down and is now speeding up again...? There is definitely something fundamentally wrong here.
Update 4: @ all very good answers (no Robert B - I don't understand, I have no idea what most of the symbols you are using mean. sorry). So let me get this right. The universe had a period of rapid expansion, whereby the space between objects grew very quickly as if we pumped up a balloon and all the marks on the surface... show more @ all very good answers (no Robert B - I don't understand, I have no idea what most of the symbols you are using mean. sorry). So let me get this right. The universe had a period of rapid expansion, whereby the space between objects grew very quickly as if we pumped up a balloon and all the marks on the surface moved away from one another as the surface area grew. Light now travels around the surface of our balloon, but it has yet to reach us from all parts of the surface. Is the observable universe expanding uniformly then, or are there lumps in the surface of the balloon?
7 answers 7