环境问题

Question

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}

\usepackage
[
        a4paper,% other options: a3paper, a5paper, etc
        left=2.54cm,
        right=2.54cm,
        top=2.54cm,
        bottom=2.54cm,
        % use vmargin=2cm to make vertical margins equal to 2cm.
        % us  hmargin=3cm to make horizontal margins equal to 3cm.
        % use margin=3cm to make all margins  equal to 3cm.
]
{geometry}
\usepackage[utf8]{inputenc}
\usepackage{algorithmic}
%% Useful packages
\usepackage{amsmath,amsthm,amssymb,amsfonts}
\usepackage{graphicx}
\usepackage{subfigure}
%\usepackage[colorinlistoftodos]{todonotes}
\usepackage[colorlinks=true, allcolors=blue]{hyperref}
\usepackage{float}
\usepackage[title]{appendix}
\usepackage{multirow}
\usepackage{pgfgantt}
\usepackage{setspace}

\usepackage{tikz}
\usetikzlibrary{shapes.geometric, arrows}


\usepackage{makecell}
\usepackage{booktabs}
\usepackage{caption}

\renewcommand{\familydefault}{\sfdefault}
\usepackage[square,numbers]{natbib}
\bibliographystyle{agsm} %harvard referencing style

\usepackage[none]{hyphenat}
\title{\vspace{-2cm} Simulation Project Report}
\author{\textbf{Authors: Jing Ting Chong, Ishaan Singh Jolly}}


\date{}
\begin{document}
Environment Problem

\end{document} 

我的环境似乎存在一些问题，我不太明白为什么以及我的 latex 发生了什么。我认为我的字体有问题，我无法使用这个将字体大小设置为我的部分和子部分 --

\titleformat{\section}
  {\normalfont\fontsize{12}{15}\bfseries}{\thesection}{1em}{}
\titleformat{\subsection}
  {\normalfont\fontsize{12}{15}\bfseries}{\thesubsection}{1em}{}