It's hard to be sure what's going on without seeing the full code you're running. One issue I can see (barely) in the picture of your code is par(oma=c(6,0,6,0)). This creates outer top and bottom margins of 6 lines each, which is squishing your plots. That's why there's so much empty white space on the top and bottom.
It will be much easier to help you for this and future problems if you provide copy-and-pasteable code, rather than images. This post summarizes how to provide data and code in ways that make it as easy as possible to help you.