Your mission should be to fit into the character, not to make the character fit into you, hence the term "costume playing". There are many characters to play as, and if you do not fit the body size requirements, please do not attempt to try.
You might be able to pull of the costume or the attitude, but the fit is very important. Nobody wants to see a fatass version of a sexy character. You would've incited killing rage amongst the fanboys/fangirls of the said character, you're just lucky that Filipinos aren't as deranged as Japanese otakus.
tl;dr: Choose someone near your body size, such as Doraemon.
Sexy Cosplay Viewer,