Test progression

I miscarried mid March after the baby stopped growing at 7-8 weeks. I bled for a week, starting on 3/17 when my body started the process naturally. After about 4 weeks, I hadn’t had a period yet, so I tested and it was a faint positive (top test). So I kept testing every 2-3 days because I thought I just hadn’t had a negative yet from my hcg getting to 0. Still no period over a week later and the last test (today) is much darker and the digital said positive. This is completely possible to be a new pregnancy, right? How do you figure out a due date without having a period before conceiving after a miscarriage? I’m so nervous and will be heading to the doctor this week.