Why does subplot size change with increasing number of plots

I am preparing a script which will prepare and print a flexible number of plots. When i have less than 5 plots everything looks fine (attached figure 1), but when i have more that 5 plots the figure size decrease and the legenbox starts to look strange (attached figure 2). How can I fix my code so my plots and legens looks like figure regardless of the number og plots.

I will need to create a long figure depending on the number of plots, and i don't need to print out on paper. Therefore I don't need to use A4 paper. My code looks like this:

      
        fig = figure;
        set(fig,'visible','off');
        
        m = 25 % This is the number of plots in total
        
        for k = 1:25
            plotdata = Matrix{k,1};
            Legend=LegendMatrix{k,1};
   
                subplot(m,1,k);
                hold on
                plot(time,plotdata,'MarkerFaceColor','auto','MarkerSize',2,'Marker','square','LineWidth',1);
                plot(Xvalue,Yvalue','Marker','o','MarkerSize',2,'MarkerEdgeColor','k','Markerfacecolor','k','LineStyle','none');
                set(gca,'FontSize',16);
                xlim([0 mtime(end)]);
                set(gca,'XTick',Xlocation);
                set(gca,'XTickLabel',Xlabel);
                xlabel('Time [days]');
                ylabel('Fluorescence [RFU]');
                title(Titles{k},'Interpreter','none');
                leg = legend(Legend,'Location','southoutside','FontSize',13,'NumColumns',2);
                leg.ItemTokenSize = [1,1]; % Legend line length and width
                box on
                hold off
            end
        end
        
        set(fig,'Papersize', [19 18*m]);
        set(fig,'PaperUnits','normalized');
        print(fig,'-fillpage','-dpdf',fullfile(DataPath,'Full.pdf')); 
        end
        
  

Figure 1

Figure 2

Answer 1

[KALYAN ACHARJYA]

I dont think figures are changing, just scaling the figure window as per the screen size (please check the scaling of plot axes, all are same)

Way out:

1. Use the following

subplot(5,5,k); % Still it gives the 5 by 5 window, total 25

2. Or print the individual window with loop and later do collage / montage function

 for 
  plot 
  print or save the plot 
 end  

See here.