37 and Positive!

I went to CVS and bought tampons and a pregnancy test hoping for the best. I was due to start that day and didn't...which is rare for me. So I went out on a limb and took the test...BAM! Instantly positive!!!! I'm about 4 weeks. I'm going through all the emotions of happy, excited, scared.... this is my first child and at 37 (38 at birth) hoping this won't be a high risk pregnancy.