Different header space after tittlepage using fancyhdr

Question

after \end{titlepage} I put \chapter*{LEMBAR PENGESAHAN} but the result is different from the next chapter's header space.

wrong space

correct space

\documentclass[12pt,a4paper]{report}
\usepackage[
  left=3cm,
  top=3cm,
  right=2cm,
  bottom=2cm,
  includehead,
  includefoot,
  bindingoffset=5mm
]{geometry}
\usepackage[utf8]{inputenc}
\usepackage[english,bahasai]{babel} % <---- main language last

\usepackage{lipsum}

\usepackage{titlesec}

\titleformat{\section}
  {\normalfont\fontsize{16}{16}\bfseries}
  {\thesection}
  {1em}
  {}

\usepackage{graphicx}
%\usepackage[colorinlistoftodos]{todonotes}
%\usepackage{showframe}

\usepackage[linktocpage]{hyperref}
\hypersetup{
    colorlinks,
    citecolor=black,
    filecolor=black,
    linkcolor=black,
    urlcolor=black
}

\makeatletter
\def\@makechapterhead#1{%
  %%%%\vspace*{50\p@}% %%% removed!
  {\parindent \z@ \centering \normalfont
    \ifnum \c@secnumdepth >\m@ne
        \Large\bfseries \MakeUppercase{\@chapapp}\space \thechapter % <--- uppercase
        \par\nobreak
        \vskip 0\p@
    \fi
    \interlinepenalty\@M
    \LARGE \bfseries #1\par\nobreak
    \vskip 30\p@
  }}
\def\@makeschapterhead#1{%
  %%%%%\vspace*{50\p@}% %%% removed!
  {\parindent \z@ \centering
    \normalfont
    \interlinepenalty\@M
    \LARGE \bfseries  #1\par\nobreak
    \vskip 30\p@
  }}
\makeatother


\usepackage{fancyhdr}

\pagestyle{fancy}
\rhead{\includegraphics[height=1cm]{LOGO_P.png}}
\lhead{\includegraphics[height=1cm]{LOGO_I.png}}

\begin{document}

\begin{titlepage}
    \begin{center}
        \includegraphics[width=5cm]{LOGO_I.PNG}\\[0.25cm]
        \textbf{xxx xxx}\\[1.75cm]
        \textbf{xxx xxx \\[4cm]}
        \textbf{xxx xxx}\\[4cm]

        \textbf{Diajukan Oleh:}\\
        \textbf{xxx xxx}\\
        \textbf{xxx xxx}\\[4cm]
        \textbf{xxx xxx}\\
        \textbf{xxx xxx}\\
        \textbf{xxx xxx}
    \end{center}

\end{titlepage}

\pagenumbering{roman}

\chapter*{LEMBAR PENGESAHAN}
\thispagestyle{fancy}
I declare that..

\chapter*{ABSTRAK}
\thispagestyle{fancy}
I want to thank...

\chapter*{KATA PENGANTAR}
\thispagestyle{fancy}
I want to thank...


\tableofcontents
\thispagestyle{fancy}
\pagenumbering{arabic}
\pagebreak
\chapter{PENDAHULUAN}
\thispagestyle{fancy}
\lipsum[1-15]
\section{LATAR BELAKANG}
\subsection{Latar Belakang}
\lipsum[16-30]
\chapter{Landasan Teori}
\thispagestyle{fancy}
\lipsum[31-45]
\begin{figure}[h]
    \centering
    \includegraphics[width=0.25\textwidth]{LOGO_I.png}
    \caption{a nice plot}
    \label{fig:mesh1}
\end{figure}

As you can see in the figure \ref{fig:mesh1}, the 
function grows near 0. Also, in the page \pageref{fig:mesh1} 
is the same example.
\end{document}