G.B.
Caffeine won't make a lot of difference unless you're drinking several pots of coffee per day or drinking a 2 liter of Mountain Dew. You have to be taking in a lot for it to make a difference like you're talking about.
I'd say cutting back to maybe a cup or two of coffee per day and a medium pop would be normal caffeine.
I think that what you need to do is get some sleep. You need to take a sleeping pill and have hubby or a friend come over and stay to take care of the kiddo's so you can sleep a couple of nights.
When I would get like this my MIL would take the kids. When she died I had my BF take the kiddo's to her house to sleep over. I got to sleep uninterrupted and after a couple of nights of good sleep I was able to function well again.
Point is, caffeine isn't your issue, lack of sleep is your issue. If you get sleep you'll be back to normal. Caffeine isn't interfering with your sleep or cognitive ability, lack of sleep is.