I've used a French press for decades now.

I've done the research and don't worry. You get a lot more caffeine, but you won't be over the danger level.

More, most of the negative side effects of too much coffee are immediate, not long term.

The key trick - try to keep all your caffeine consumption into a fairly narrow time window, because caffeine has a half-life in the body of about five hours, so even ten hours after you had a cup of coffee, 1/4 of its caffeine will be in your system.

Also, if you take somewhat more caffeine than usual and it doesn't work, taking more won't really work much better. Drink water, maybe some vitamin B, and remember that some days are low energy days, so don't worry.