from an employer point of view,if you are interviewing a lot of people, you are generally looking for someone who stands out from the crowd by that I mean someone who is going to bring that little bit extra.
size will matter I `m afraid dependent on the work, but not necessarily.
I have employed all shapes and sizes through the years, so don`t be downhearted , the right job will come to you.
a bit of advice always look and take a positive attitude away from every interview, look upon all interviews as interview experience. obviously try to look as if every interview you attend is the most important , the interviewer will pick up a lot from your body language etc.........above everything remain positive you will succeed