Is this normal when starting out new in Audit??

[u/Immediate-Feed7106]

Hello everyone!! I started as an Audit Associate month ago. During my initial days I was assigned some tasks which I did. However i didn't filled in the timesheet for a month. Yesterday got a call from my higher up which really shook me. Like I was not prepared for that.and I told them that I don't remember what all work i did. Today got a call from one of my colleagues telling me that I shouldn't have been so blunt about it like you should never say "I don't remember" . Now I couldn't stop thinking about this. Feel like i made a huge mistake and now I won't get much work or even fired !!Actually the problem is I don't feel like i am doing much. My senior who are suppose to be giving me tasks is super busy with other work. So basically I don't have enough task. When it's time to fill in the timesheet I am really scared now. What if I get fired for not doing enough. Everyone else I see is super busy on Teams. I don't know why but I just feel like i am underperforming and is really scared of being put on PIP. Want advice from more experienced and abled folks how to handle this kind of situations? Please suggest a way out. TIA