So Nervous!

I just found out I'm around 4 weeks pregnant at the beginning of this week. I'm a nurse, so after I took my home test, I confirmed with labs at my office. Hcg was 47. I've felt okay overall and scheduled my first ultrasound and appointment for March 6th. Today I noticed some brown spotting which I know can be normal but I'm starting to freak out as this is my first pregnancy and was not planned. Any advice?