Minimizar el espacio en blanco debajo de la figura

Question

Intenté seguir algunos hilos para minimizar el espacio en blanco debajo de mi figura. Parece sencillo, pero no funciona. ¿Quizás podría ser que esté intentando hacer esto en un entorno Apéndice? Me gustaría ampliar mi figura de 16 cm a 18 cm (sí, hay suficiente espacio en la página para esto), mi intento se ve así

\documentclass[a4paper, leqno, oneside] {report}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lscape}
\usepackage{caption}
\usepackage{subfig}
\usepackage[section]{placeins}
\usepackage{amsmath, amsthm, amssymb}
\usepackage{listings}
\usepackage{url}
\usepackage{longtable}
\usepackage{multirow}
\usepackage{verbatim}
\usepackage{kbordermatrix}
\usepackage{graphicx}
\usepackage{listings}
\usepackage[table]{xcolor}
\usepackage[swedish, english]{babel}
\usepackage{hvfloat}
\usepackage{booktabs}
\usepackage[textwidth=15cm, textheight=23cm]{geometry}
\usepackage[nottoc]{tocbibind}
\usepackage[toc]{appendix}
\usepackage{rotating,caption,booktabs}

\begin{document}
\section*{Appendix 5}
\addcontentsline{toc}{section}{A.5 my figure}

\begin{figure}[h] 
\centering
\caption{My very big picture}
\setlength{\belowcaptionskip}{-2cm}
\includegraphics[height=16cm, width=1 \linewidth]{QQmale1.png}
\label{fig:QQmale1}
\end{figure}    
\end{document}

Answer 1

debe reducir la proporción predeterminada de texto en la página. intente agregar \renewcommand{\textfraction}{0.05}al preámbulo del documento:

\documentclass[demo, % only for test purposes
                a4paper, leqno, oneside] {report}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lscape}
%\usepackage{caption} % loaded second time
\usepackage{subfig}
\usepackage[section]{placeins}
\usepackage{amsmath, amsthm, amssymb}
\usepackage{listings}
\usepackage{url}
\usepackage{longtable}
\usepackage{multirow}
\usepackage{verbatim}
\usepackage{kbordermatrix}
\usepackage{graphicx}
\usepackage{listings}
\usepackage[table]{xcolor}
\usepackage[swedish, english]{babel}
\usepackage{hvfloat}
%\usepackage{booktabs}  % loaded second time
\usepackage[textwidth=15cm, textheight=23cm,
            showframe  % only for test purposes
            ]{geometry}
\usepackage[nottoc]{tocbibind}
\usepackage[toc]{appendix}
\usepackage{rotating,caption,booktabs}

\renewcommand{\textfraction}{0.05} % <---

\begin{document}
\section*{Appendix 5}
\addcontentsline{toc}{section}{A.5 my figure}

\begin{figure}[htb]
\centering
\caption{My very big picture}
\includegraphics[height=0.88\textheight]{example-image}
\label{fig:QQmale1}
\end{figure}
\end{document}