Small gestational sac at 39 years old

I am 39 and found out I am pregnant. I really need to hear some success stories please as I am sick thinking I am going to miscarry. I’ve had a miscarriage 8 years ago with no live children. I’ve had only brown spotting, light cramping since last week. No heavy bleeding or heavy cramps. I’ve been getting my levels drawn and ultrasounds every two days. My hcg levels are low and progesterone levels are low. The doctor put me on progesterone pills. I’m technically 6 weeks 2 days according to my period but the gestational sac is reading 4-5 weeks. Im scared and wondering if anyone has been through this and had their baby successfully.