Slow rise in HCG levels, miscarriage?

Hi!

31 days after my period, I had an hCG level of 293. My GP said it was on the low side and advised me to get my blood drawn again a week later.

Exactly one week later (so at 5 weeks + 3 days), the level had only risen to 610. It was a punch in the face, because I know it should roughly double every two days. Now it only doubled over a full week. My GP downplayed it a lot and said the most important thing is that the levels have risen. He said he thinks I’ve definitely implanted and wished me congratulations. I’m having trouble believing this and expect a miscarriage. I still have to wait two weeks before I can see the gynecologist.

With my previous (full-term) pregnancy, I only had my level measured at 5 weeks, and the hCG level was then more than 4500. Before that, I had a miscarriage and the hCG was 270 at 7 weeks. I do have some pregnancy symptoms right now (tight breasts, a bit nauseous), but I feel less tension in my belly than in my previous pregnancy.

Do you think this can still turn out okay? Anyone have a similar experience? Should I trust my GP more or does my feeling hold water?