Welcome to the Forum.. I'll try to help. concerns about hepatitis C as an STD are wildly over blown. The infection is quite uncommon unless your partner is an IV drug user (past or present) and even then most people do not have infection. Hepatitis C IS OCCASIONALLY transmitted through receipt of receptive rectal intercourse. Transmission is exceptionally rare among persons through vaginal intercourse and I am not aware of any cases reported to have occurred following either giving or receiving oral sex- none! Further, while THEORETICALLY possible, transmission through immediate sharing of a toothbrush is simply not seen.
In your own case, your negative test, combined with the tiny risk for infection, virtually assures you that you are not infected. From a medical perspective there is no reason for concern or for further testing.
I hope these comments are helpful. Please don't worry. EWH
Thank you very much for your answer.