Did anyone start with low hcg and things turned out fine?

Shikha

So for the whole week I have been getting faint but clearly visible lines on home tests. I went in for 1st blood draw on 29th September and the beta hcg was 8.25… 2nd blood draw was 51 hours later and the result is 15.66. It almost doubled but I didn’t give it 72 hours as they say. M worried about what’s going on.