This is completely normal. This is the begining of motherhood and just the start of all the fears.
Next fear: you'll worry if the baby is moving enough.
Another fear: are you eating well enough.
Later pregnancy fears: labor & delivery.
That is when the real fun starts and the baby is here (remember, pregnancy is only getting the baby here, after the baby gets here...well, the world changes completely!) - you'll worry about everything. Is s/he sleeping enough? Too much? Eating right? Too much? Too little? Is it a cold or allergies? Diaper rash? What cream to use?
You are fine. The baby is fine. Relax and enjoy the pregnancy, the real work starts later.