Is it normal feeling like this? 3 days old son.. FIRST TIME MOM

So I just had my son July 13 2017.

I'm 18 years old and ever since I brought him home I'm so constantly worried about him choking or anything happening to him. I can't sleep at all because I always watch him. Also I've been crying and having anxiety.i don't know if it's normal to feel like this or what but I just can't wrap my mind around the fact that I have a baby. Cause I never believed I was pregnant and now I have a beautiful baby boy. Has any first time mom experienced overwhelming and anxiety when they bring their baby home? not getting sleep?