Soda and pregnancy

I'm 14 wks 4 days and just started getting morning sickness, body aches and terrible fatigue at around 10 weeks.

I'm a working mom and can't afford to take much time off.

I've been keeping up with a healthy diet and no caffeine... but yesterday I had about half a can of Coca-Cola during the lunch hour and felt amazing!

My aches stopped, I had energy, headache was gone, nauseous feeling went away, it was great.

But is anyone else taking in caffeine in moderation?

How safe is it?

My Dr adviced that 1-2 cups a day should be okay if necessary.

This is my first pregnancy. So I'm a bit worried.

Thanks and have a great day!