I need caffeine!

I’m 6 weeks today and the exhaustion is getting to me so bad! I’m averaging 2-4 naps a day. I’m about to go back to work after finding out and a late Christmas vacation and I work nightshift. I understand that under 200mg of caffeine is recommended, but what I need to know is can I drink energy drinks? Redbull, rockstar, lotus, Celsius? I’m not a coffee drinker at all, but I’m dying. I’m still two and a half weeks out from my first OB appointment so I can’t ask my doctor right now, and this is my first pregnancy. Please help a new mama out!