Does this girl is flirting or love me or just playing?

Hi, i am at high school..there's one shy girl at school. She always mimic my body movement at class (how i sit, writing, mimic all my movement), Sit infront of me or diagonal, Keep look at me but sometimes turn away when i notice her, when her friend saw this girl sit near me at class they sometimes talk behind me or laugh, When walking at hall she lock eye contact with me then look away. After i notice those signals, i decide to flirt back..then i start mimic her,give eye contact ect ect. i gave her compliment by telling her friend "she look better with pigtails hair". Tomorrow, when she saw me at class..she began to change her hair looks to pigtails hair and always try to get my attention by walk infront of me without reason anytime...i am so confuse..what should i do?? i sent her love letter but no respond till now (maybe because she's shy)..and we are holiday till 25 july..should i wait till 25 july and see her respond at school?? or should i gave up on her because she's just playing with me? we never talk to each other school,class and we just flirt with each other till now..anyone pls help me ok