Hcg barely rising?

On last Wednesday they took my blood and again on Friday, they said it only rose by around 200, they were around 7242 on Wednesday. So it was around 7442 on Friday. It would have been a little less then 40 hours apart because Wednesday was later in the evening and Friday was early in the morning. I'm really worried. I haven't had any sort of bleeding or cramping but you never know. Help??