Go for it! I wouldn't think you were ever too old/young for that sort of shoe they're a pretty classic style (I'm 23 and my aunt (60+ has a pair not unsimilar). As for your size, who cares? They are shoes not anything revealing and even if they were whatever you are comfortable and confident in is what you should wear.
Buy them, rock them and know you look great as long as there is a smile on your face and confidence in your walk!