Is it safe to take this much Tylenol?

I'm suffering with chronic tension headaches. Constant pressure around my head and eyes. The only thing that seems to work, is Fioricet. Thing is, it contains 325mg in each tab. I've been taking it nearly everyday, for the past month. The most I've ever taken in one day, was 6 tabs. But that only happen twice. I usually try not to take more than two. There were a few days, I just didn't take any. Just because I was scared of the tylenol, and what it could possibly be doing to my liver. I don't want a damaged liver. But I don't wan't to live in misery either. I know fioricet can become addicting, and my neurologist gets this weird look on his face when I ask him to prescribe it, then gives me the lecture on how it has a dependency. I KNOW IT DOES! I'm not that low that I'd try to get off on pain meds, people don't understand. I'm losing my mind with these headaches. My eyes always feel battered, can't look left or right, without having my eyes gouged with pressure. Back of head feels like it's going to explode. I've already had 3 CT scans, MRI and a spinal tap. They can't tell me what's wrong, and it's really depressing. I just want my life back :(