Math is the language of logics. You cannot talk about complex logics without maths. Physics uses maths extensively because there are regularities in nature that can be represented by maths. Maths describes that regularities or patterns precisely, and according to logical rules established in maths, these equations of nature phenomena can be manipulated in forms and structures to yield different perspectives of the same reality. Like looking at the other side of the same coin. In physics, without maths, you can hardly formulate your idea for others to test it out, which again calls for maths to know if the test is good or not. Again the reason being that we expect nature to be rational and consistent, like if we throw the same ball over and over again, we expect to see the same trajectories which can be modeled by maths.

If you want to know something about string theory and the practice of science, read this book

The trouble with physics by lee smolin

http://www.thetroublewithphysics.com/

It is one of the best science books I read in years.