[Tex/LaTex] text not justified

horizontal alignmentmargins

I am new to LaTeX and in my first article I am facing the following problem.
Although I set the margins to 1 in all around the A4 page, the text does not justify till the end of the right margin. It justifies almost one 1 in before the margin.
Header and footer follow the margins but the texts isn't. 

\documentclass[12pt,a4paper]{article}
\usepackage{lipsum}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage[lmargin=2.5cm, rmargin=2.5cm,tmargin=2.50cm,bmargin=2.50cm]{geometry}
\usepackage{lastpage}
\usepackage{setspace}
\singlespace
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\renewcommand{\headrulewidth}{0.5pt}
\fancyhead[l]{MSc Lift Engineering\\LIFM005DL-Assignment LCK}
\fancyhead[r]{Christoforos Milionis}
\renewcommand{\footrulewidth}{0.5pt}
\fancyfoot[l]{30/05/2013}
\fancyfoot[r]{Page \thepage\ of \pageref{LastPage}}
\usepackage{graphicx}
\usepackage{caption}
\author{Christoforos Milionis}
\title{2nd Assignment}
\begin{titlepage}
\begin{document}
\begin{minipage}{0.10\textwidth}\begin{flushleft}
\end{flushleft}
\end{minipage}
\begin{minipage}{1.1\textwidth}\begin{center}
\LARGE\textbf\\ Oadsdadsn \\
\Large dassdasdas
\end{center}\end{minipage}
\begin{center}
\vskip2.5cm
\LARGE \textbf{dhdjdj uygkygk}\\
\large Student No. jyfgkugy
\end{center}
\vskip6cm
\large \ \ \ \ \ \ \textbf{Supervisor}
\par  \ \  hgfhdfj hgkhg
\end{titlepage}
\doublespace
\tableofcontents
\newpage
\section{Assignment Brief}
\doublespace
\lipsum[23]
\end{document}

This is the preamble.

Best Answer

You have a very big header for the default header height; so fancyhdr warns you and pushes the material down the page. This is what you get in your log file

Package Fancyhdr Warning: \headheight is too small (12.0pt):
 Make it at least 27.18335pt.
 We now make it that large for the rest of the document.
 This may cause the page layout to be inconsistent, however.

Never underestimate warnings; for instance you get also other warnings, see later.

A way to fix it is to say

\usepackage[margin=1in,headheight=28pt]{geometry}

The other warning you get is 

(\end occurred inside a group at level 1)

### semi simple group (level 1) entered at line 48 (\begingroup)
### bottom level

which is due to incorrect usage of \doublespace which should be \doublespacing.

Also move \begin{titlepage} after \begin{document}.

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