Superstring Theory- 9 dimensions of reality?

So I'm reading Fabric of the Cosmos by Brian Greene and I'm about 20 pages in and so many questions already popped into my head.

Bear with me that you might seem kinda lost reading this because I'm not going into detail about this cause I would need 20 pages to fully explain this. Just listen and accept the facts that I give you.

So physicists can use quantum mechanics to predict the probability of motion and actions in time for small matter and relativity theory to predict the same for large matter like stars and galaxies. They however cannot mix. Because for probability is measured in percent 20% 34% etc. But if you mix the two theories you get an infinite percent. Now you may think alright so if there is an infinite percent chance that the colts will win then I'm gonna bet all my money on them. Well it doesnt work that way. Probabilities higher than 100 are meaningless. They represent innacurate information.
Now what about the centers of blackholes? Or the legendary Big Bang?

You can't just use one of the two theories because of the huge amount of mass each one has. So physicists have spent years trying to come up with a theory of reality in which quantum mechanics and relativity theory can exist together in peace. After decades they came up with Superstring Theory.

Superstring theory functions on the fact that all the electrons and quarks that make up atoms and such are actually strings. Extremely small strings vibrating on different frequencies. When a guitar string vibrates it creates a musical note, well Superstring theory functions on the same idea except instead of notes, we get matter.

Makes sense so far right? Well Superstring theory poses a giant twist on reality. Instead of there being 3 dimensions of space, height width depth, and one dimension of time there are 9 dimensions of space and one dimension of time. Now what does this mean? We cant deny Superstring theory though because it answers many, many questions in cosmology etc.
So now what are we missing out on? What is reality?