Pregnant after miscarriage

I got pregnant in December 2020 and cane to know about it in January.My hcg levels started dropping and i had a miscarriage.Took misoprotosol on feb 2 and bled till feb 10.

I had sex on march 1 and march 15.

I was feeling some symptoms so took a pregnancy test randomly and it came out positive.

Blood work says hcg is 700.

I am really very happy because i had miscarriage at my first attempt.

But now i want to know how many weeks pregnant I am ?

As I didn’t get periods after miscarriage bleeding,how should I calculate?

I am scared at the same time.

Please pray for me and my baby🙏