Concerned

Hi so I’m 19 and pregnant I had really light brown bleeding no pain or cramping what so ever but I went to the doctor. He sent me to do an ultrasound at 4 weeks 2 days. I had a slightly irregular gestational sac, no fetal heart rate or well defined fetal pole was identified ( maybe too early). I was told early pregnant lost is likely. I went to do a blood test my hcg levels were 1476 and in 48 hours it was 3005 doctor said pregnancy is progressing but I’m still scared has anything like this or similar happened to anyone of you ? I’m 5 weeks 1 day today