I can't change the font size [closed]

I can't do something so simple like changing the font size . No matter what number I write in `\documentclass[10pt]{article}`, I'm not able neither to reduce nor to increase the size.

Although after `\documentclass` you can see `[10pt]`, reality is that the actual font size the text is compiled is 11 (I think).

I wonder if the problem has its root in any of this packages:

``````\documentclass[10pt]{article}
\usepackage{amsmath,amssymb,amsthm,fontenc,titlesec}
\usepackage[left=2.5cm,top=3.5cm,right=2.5cm,bottom=3.5cm]{geometry}
\usepackage{lipsum}
\usepackage{graphicx}
\usepackage{wrapfig}
\usepackage[spanish]{babel}
\usepackage[latin1]{inputenc}
\usepackage{fancyhdr}
\usepackage{multirow}
\usepackage{url}
\pagestyle{fancy} % seleccionamos un estilo
\lhead{TEBF} % texto izquierda de la cabecera
\rhead{Jorge Becerra} % número de página a la derecha
\renewcommand{\headrulewidth}{0.4pt} % grosor de la línea de la cabecera
``````

• Welcome to TeX.SX. The valid values are `10pt` (default), `11pt` and `12pt`, is there no change with the two latter? – Torbjørn T. Apr 6 '14 at 19:55
• How do you know the size? I'd expect `10pt` here. For larger text, I'd use `{\large my words}` and so forth. See this link for more information. – jon Apr 6 '14 at 19:57