Happiness is great!
If one doesn't want to be pregnant, and is happy her period finally came, that's great! if one wants to be pregnant, and is happy she missed her period, that's great too! it's nice to be happy.
If it's important to know if one is pregnant, just do a urine pregnancy test
from the store (they are very accurate). If there is no urgency, just wait to see if other symptoms of pregnancy start appearing.