Could you please let me know how many themes are there

I am trying to install a theme which fits my actual site the best (www.astrotrends.net) but I couldnt find anything yet. Can you suggest any to me?

Also, I thought there were hundereds of themes and there are only a few it seems. How can I see all the themes and any idea how many are there in total?

I got this two months ago and still havent been able to use even one theme yet. Quite confusing it seems as each theme only comes with a shell and it is too cumbersome to create custom which doesnt look like the one advertised at all.