[chrispenycate]

A question of scale. A city feels big, to a human being, but if you fly over a country, there is far more open space tham city. A planet is much bigger than a country, but even so, we're only seeing the surface layer, the mould on the cheese.
Most asteroids (the name is wrong; they should have been "planetoids", but it was established before their situation was well understood) we can detect are in the "country" to "continent" size range. There are obviously many, many smaller ones, but they're a bit more difficult to see, unless they impact the Earth. Anyway, by the new definition, a planet has to orbit a star; if it orbits something else it's a moon (which can make some moons bigger than some planets, but that's how it is)
Going up one in scale, a solar system is almost entirely empty space. Almost everything that isn't empty space is star (your average sunspot, almost invisible on the surface, could swallow Jupiter, and Jupiter's red spot, a storm system, could swallow Earth. Without belching.
Of the remaining matter in the solar system, most (over 90% each time for these "mosts") is gas giant planets. The tiny remander is rocky stuff, including Earth, which we've already demonstrated is quite big in its own right.
A cluster of a few hundred of these stars, along with dust clouds and various junk (it is quite possible that the total mass of comets is higher than that of planets) sort of coagulates together in a few thousand times the space of the solar system, and many thousands of these, along with odd nebulae and things make up one spiral arm of the galaxy. The core may well be considerably stranger, but we can't see it. By now, light is taking thousands of years to get here from where we are describing, so a trip to go and see, even at light speed,(apparently the absolute speed limit in our universe) is going to take longer than human civilisation has been around.
So, without needing to check out other galaxies, you've got enough potential space, and potential strangeness, to keep a writer going till the sun becomes a white dwarf. Any bigger is just one-upmanship.

Now, a personal point. If you'reintending to become a writer, why not practice your skills while posting? And one which will be essential is punctuation (waves down jeers and cat-calls: yes, I know I'm always on about peoples punctuation, but believe me, it's important)
Maybe, when you are established you'll be able to get away with writing like that, but until then it makes me want to leap for my red pen; and others will feel the same if you submit manuscripts like that.

Finally, your musicians parallel; while many, if not all, successful musicians will like music outside their particular genre, I have worked with several hundred groups and session musicians and they would not be playing the style they've chosen if they didn't like listening to it, and similar work. No musician can give his best if he doesn't get into the music; and there are enough musicians waiting in the wings (or playing in holiday inns) that, without your best, you are doomed to extinction.