Thanks for the query to H.C.M. Forum.
As your last menses date was on 6th September & period was 28 days regular so it was too early for home pregnancy
test in first test .
That was the reason the in 1st test test line was dim ( faint) , in 2nd test you clearly saw the line and pregnancy test was positive .
Similarly is the case in blood test
level , it is normally 100-500 ng/dL in luteal phase ( in your case although very low ,but due to very early stage testing).
In my opinion there is no chance of miscarriage
but still consult a gynecologist and get his opinion.
Get in one more blood test for hcg for elevation level for confirmation of pregnancy .
Good luck. Dr. HET