Introducing myself

Hello ladies! I'm currently 4 weeks 5 days pregnant. I've been trying to conceive using donor sperm for about 3 years now. After being 3 days late for my period I decided to test and 5 tests later I'm pregnant! Went for blood work today and my level was 645 I have to go back in two days to make sure it's increasing. Now I feel so anxious and I'm worried about it not doubling. Any words of advice to try relaxing? I just want a healthy baby! But then again don't we all?