Pregnant or Anemic? How can you tell?

They have the same symptoms for the most part. I think my GF might be pregnant. But we also just gave blood a couple of weeks ago. She is tired and fatigued recently. She is having headaches. She usually has cracked lips. She is having a period right now...that's why I don't think she's pregnant. It's a heavy period, when she usually has light ones. But I have heard of people still having heavy flow periods and being pregnant! What do you think is up?