So tired!

Im almost 9 weeks, no morning sickness but im SO tired! When I went to the doctor to confirm I was pregnant there wasn't anything said about what I could or couldn't eat or drink. I want coffee! Can I actually have a small cup? Even if I dont actually finish it (which I rarely drank any or even a full cup before I knew I was actually pregbant)? It's just so hard for me to keep my eyes open at work! Ladies? :)