What is Brahmand / Universe ?

According to the scriptures (especially Brahmanda Purana) , there are countless Brahmand or Universes .

Each of them are egg shaped and each of them are covered by fire , water , earth , air , ether , mind , intelligence & false ego .

Now , are the scriptures reffering our galaxy or solar system to be the universe ... or does our scriptures mean the universe itself holds all galaxies & solar systems inside it , as modern science says ??


Also the earth / bhuloka is believed to be at the centre of the universe according to our scriptures . Above bhuloka lies 7 upper lokas ... and below bhulok lies 7 lower lokas .

This means our universe has only 15 lokas in total including earth (bhulok) .

Is the universe really that small ?? Only 15 planes of existence ??
If its that's small , then could it be , that the scriptures are actually referring our galaxy or solar system to be the universe ?


I'm a little confused here ... Would appreciate if someone enlightens me on this matter .
Also are there any sanskrit terms for galaxies & solar systems ?

Thanks & Hare Krishna :)