20 month speech

My daughter does talk. She follows muti step directions. She was born 6 weeks early. She listens. We read, we sing. She can identify what she wants when I ask milk or yogurt. She can empty the dishwasher and knows where things go. She knows how to push the chair to get water out of the fridge. When I ask where certain animals are she can get them.

Should I be concerned about the lack of saying a new word every week or saying two part sentences?

Is it just me?