I'd strongly recommend you reconsider your method of deliverance. Sepsis is not a peaceful or painfree way to go. If it does kill you it could take longer than a few days or even a few weeks. This is especially true if doctors are trying to save you. Injecting dirty crap will also cause painful swelling and possible open wounds. Depending on the bacteria it could be manageable for the medical staff or it could be horrid and messy. You could lose a limb, require skin grafting, cause damage to your organs. I know that this probably doesn't matter to you if you think you'll be dead, but there's a good chance you won't die. The doctors could very likely save you and then you'd have to deal with the consequences of your method.
It won't be fast, it won't be pain free, you probably won't die and as such will have to deal with all sorts of damage. You will probably make your current situation much worse.
I really strongly advise you to reconsider.
Further, you're assuming you'll end up with sepsis. You may not, or you may not until after having dealt with bacterial infection outside of your blood stream.
What will you do if you end up worse off than you are? What if you survive and get admitted to a psychiatric hospital? What if you're left unable to care for yourself? What if you're left unable to kill yourself? That's a big one to consider. You may of yourself in a position where you are alive, but don't want to be but can't do anything about it due to complications from your attempt.