i suck vocally practicing but it happen sometimes

I work really hard to sing good but sometimes in practice and sometimes in performance - i dont have a good day but it happens for vocalists,- even among the best vocalists , i used to be just a rock singer, now i am a pop singer , i sing soprano, but i stay in tenor all of the time ,baritone,but sometimes i cannot sing in soprano - but i am singing in practice just to write- not for people to hear- but even than i have bad days and thats ok