i can’t seem to help but be scared

i miscarried last year and when i found out i was pregnant with my rainbow instead of excitement i felt nervous and scared. i’m almost 5 weeks. test have gotten darker. hcg levels are rising like they should. and regardless of the good news i keep hearing , all i can think about is that when i go into my doctors on the 17th of december , they’ll tell me the baby isn’t growing or there isn’t a heart beat :( everytime i go to the bathroom i look for my period. i hate being worried and i hate over thinking and idk how to stop