Table of contents with fancyhdr

I attach my MWE.

documentclass[12pt, twoside]{book}
%documentclass[journal=jctcce,manuscript=article]{achemso}
usepackage[a4paper, vmargin=2.5cm, hmargin=2.0cm]{geometry}
usepackage{times} %czcionka Times New Roman
usepackage[latin2]{inputenc} % For english
usepackage{fancyhdr}
usepackage[Bjornstrup]{fncychap}
usepackage{longtable}
usepackage[nottoc,numbib]{tocbibind}
usepackage[bottom]{footmisc}
definecolor{mygray}{gray}{.60}

pagestyle{fancy}

newcounter{chaptercounter}
newcounter{sectioncounter}[chapter]

renewcommand{chaptermark}[1]{markboth{#1}{}}

fancyhf{}

fancyhead[CO]{rightmark} %central odd-number page (section name)
fancyhead[RO]{%
  textcolor{black}{%
%    rightmark
    rlap{%
      hspace{1pt}%
%      hspace{-fboxsep}%
      colorbox{mygray}{%
        makebox[textwidth][l]{thepage}%
      }%
    }%
  }%
}

%fancyhead[RO]{thepage}
fancyhead[CE]{thechapter. MakeUppercase{leftmark}} %central even-number page (chapter name)
fancyhead[LE]{%
  textcolor{black}{%
%    rightmark
    llap{%
      hspace{marginparsep}%
      hspace{-fboxsep}%
      colorbox{mygray}{%
        makebox[textwidth][r]{thepage}%
      }%
    }%
  }%
}

%Usuniecie numerow stron w stopce
fancyfoot[CE,CO]{ }





begin{document}

fontencoding{T1}selectfont %DLa pogrubienia Times New Roman


thispagestyle{empty}

begin{center}
hugebf
DOCTORAL THESIS
end{center}


newpage
frontmatter


chapter{Acknowledgements}
thispagestyle{empty}


thispagestyle{empty}
fancyhead[CO]{MakeUppercase{Contents}} %central odd-number page (section name)
fancyhead[RO]{%
  textcolor{black}{%
%    rightmark
    rlap{%
      hspace{1pt}%
%      hspace{-fboxsep}%
      colorbox{mygray}{%
        makebox[textwidth][l]{thepage}%
      }%
    }%
  }%
}
%fancyhead[RO]{thepage}
fancyhead[CE]{MakeUppercase{Contents}} %central even-number page (chapter name)
fancyhead[LE]{%
  textcolor{black}{%
%    rightmark
    llap{%
      hspace{marginparsep}%
      hspace{-fboxsep}%
      colorbox{mygray}{%
        makebox[textwidth][r]{thepage}%
      }%
    }%
  }%
}


tableofcontents{}
pagestyle{fancy}
fancyhead[CO]{MakeUppercase{leftmark}} %central odd-number page (section name)
fancyhead[RO]{%
  textcolor{black}{%
%    rightmark
    rlap{%
      hspace{1pt}%
%      hspace{-fboxsep}%
      colorbox{mygray}{%
        makebox[textwidth][l]{thepage}%
      }%
    }%
  }%
}

%fancyhead[RO]{thepage}
fancyhead[CE]{MakeUppercase{leftmark}} %central even-number page (chapter name)
fancyhead[LE]{%
  textcolor{black}{%
%    rightmark
    llap{%
      hspace{marginparsep}%
      hspace{-fboxsep}%
      colorbox{mygray}{%
        makebox[textwidth][r]{thepage}%
      }%
    }%
  }%
}

chapter{Foreword}
thispagestyle{empty}


chapter{Glossary of abbreviations and symbols}
thispagestyle{empty}

chapter{ch1}
chapter{ch2}
chapter{ch3}
chapter{ch4}
chapter{ch5}
chapter{ch6}
chapter{ch7}
chapter{ch8}
chapter{ch9}
chapter{ch10}
chapter{ch11}
chapter{ch12}
chapter{ch13}
chapter{ch14}
chapter{ch15}
chapter{ch16}
chapter{ch17}
chapter{ch18}
chapter{ch19}
chapter{ch20}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}
chapter{ch21}

end{document}

I want the central part of the header in table of contents to say "CONTENTS" on both odd and even pages. It does not work on the odd page in this case.