plotting – PlotLabels Cut off in Show

When I try to use PlotLabels with Plot that is in Show, it gets cut off.

Show(
 ListPlot({eulerN8,eulerN16,eulerN32,eulerN64}, Joined->True, 
  PlotStyle->{Black,Darker(Green),Blue,Red},Mesh->All, AspectRatio->1, 
  PlotLegends->{"n = 8", "n = 16", "n = 32", "n = 64"}),
 Plot(y(x),{x,a,b},
  PlotLabels->"True Solution", PlotStyle->Lighter(Purple)),
 PlotLabel->StringForm("y' = ``, y(``) = ``n Euler method solutions with different step-sizes",f(x,y),x0,y0),AxesLabel->{x,y}
)

Note the single grey pixel on the upper right side of the image, that is absent when PlotLabels is absent.

Note the single grey pixel on the upper right side of the image, that is absent when PlotLabels is absent.

Does anyone know how to fix this? Manually adjusting the plot range fixes it, but there’s got to be a more professional looking way than that right?