10 dpo- Am I Preggo?? 2 miscarriages and 15 months of trying!

So, I have had 2 miscarriages and 15 months of trying, and had these today at 10 dpo:

Then, I went and got a blood test, and it came back 5.2, so barely pregnant, but it was confirmed.

Then, I came home and took another First Response test, and it was totally negative just a couple hours after the one before, which was the darkest one of the day!

I drank about a liter of water over the course of a couple hours. I'm guessing that the urine was just diluted, and 5.2 is super low to get a positive for anyway, but I wanted to post for some reassurance. I've been trying so long with miscarriages so just a bundle of nerves and wanted to post for sure reassurance.