First of all, I'm very sorry to hear you had a miscarriage last month.
Have you had another period since then or was the 2 day bleed the first? It can take a while for your periods and cycle to get back to normal after a MC unfortunately....and there can also be hcg left in your body which can show up as a positive test for weeks afterwards.
Of course it could also be implantation bleeding and you could actually be pregnant again.
Either way, tonight's test doesn't count I'm afraid as it's nearly 3 hours later when you saw the line so highly likely to be an evap line.
You're going to be better off doing another test in the morning with FMU and seeing if anything comes up within the 5/10 minutes stated on the packet.
Good luck x