low HCG levels. I could use some success stories :(

Hey, so I got my HCG levels taken yesterday. Came back at 19. I'll go back in for another blood draw to see if they've gone up.  Went to my doc today. He was very concerned with 19. As it is very low. If I miscarry, it'll be my 4th. I'm hoping to see my levels shoot up. I'm 4 weeks tomorrow. Any success stories out there of HCG levels starting out very low at 4ish weeks and still having a healthy thriving pregnancy??