I'm soooo confused right now

Helen
I'm soooo confused right now! My boobs were a bit tender and I felt slightly bloated so I did a pregnancy test and it's a positive! It says 2-3 weeks. I'm absolutely over the moon as we've been ttc for 7 months for our second. The bit I'm confused about is I've had a period in between then! I've worked it out that we must've conceived on the 3rd July but I came on my period on the 6th.
I'm also bleeding a little bit at the moment but it's that really dark brownish blood so am I pregnant or am I having a miscarriage, how do I know?!