You only have to go to a party to see how little size and shape really matters, it's confidence that does the trick, if you have a sexy attitude people will be attracted to you. I've only been to two parties so far but at both there were larger men and ladies (me included) and we all got plenty of very positive attention, nobody was looking in disgust because we may have the odd extra-curvy bit on us! I certainly wasn't thinking 'eww he/she is fat I'm not playing with them!'
It is only natural to be attracted to a certain 'type' but as long as it's not to the exclusion of all others you won't miss out on some fantastic experiences. Some of the best experiences I have had were with people I wasn't immediately attracted to at first, so you never know until you try!