Im Having Cough For About A Year I Guess Maybe

im having cough for about a year i guess maybe a little less.. for the first few months i had a check up with a doctor and said it was allergy. so i took it lightly. my parents noticed that my cough is not going better but it doesnt worsten. there are time that i dont cough and there are times that i cough alot. sometimes when im occupied to something i dont cough and sometimes when i hear someone coughing i cough too. what might be the cause? ill be having my check up in a few days