What should i do about this hair problem?

every few hours my hair creates oil and it gets very uncomfortable especially when i wear glasses. what i do is wash my hair, but if i wash my hair too much my hair turns flat and i dont want that, but i dont want dandruff and oil too. i heard you should wash it every 2-3 days but i cant last that long but i want not flat hair while not having oil. is there a way to fix this problem?