The range that Melbourne pathology use for quantitative hcg are:

3-4 weeks: 9-130
4-5 weeks: 75-2600

If you are only just at 4 weeks then while the level is technically a little low, I definitely wouldn't lose hope as hcg levels can vary by a huge amount. Also, if implantation happened later than usual then bubs may not have had enough time to make lots of hcg yet. I won't tell you not to stress (because I know how impossible that is), but think positively that you test today will reveal a much higher level for you. You can always ask your doctor or the nurse taking your blood to mark the test as urgent so you can get the results back faster. I explained how stressed I was to the nurse taking my blood one time and she put the urgent sticker on the test and I had the hcg level back within a few hours.

Good luck sweetie!!!