I forget if this is an anime or a manga, but it has a girl who, whenever she tries to smile, creeps out everyone around her. However, she can smile when not told to, and this smile is quite nice.
In her class, there is a male and female top of class (decided by grades), and these people get to wear a silver (I think) clip on their uniform, and this clip enables them to get free food from the cafeteria. These people are the class representatives, and they help out with class duties.
However, there is another girl who is jealous of her. This girl had been the top of the class for years. At one point steals the other girl's bag. However she trips and falls onto the male MC. She also declares herself the other female MC's rival, although the female MC does not really notice this.
One final note is that for the first bit in the anime/manga, the female MC would try to smile at her rival, but because her smile is so messed up, the rival would interpret the smile as being condescending.
EDIT: Also, she is quite socially awkward, and she has to look up what it means when she is experiencing certain emotions...like the heart beating fast. She also sends random emojis as well.
Also, this is neither Kimi no Todoke nor Watamote.
Thanks!