Pregnant after loss

Hi ladies! So I lost my baby at 5 weeks 1day on April 8th. I figured my hcg levels would have pretty much leveled off by now. My bf and I haven't been actively trying we've been using the withdrawal method. I just took two pregnancy tests one on May 23rd and one on May 25th I would have though the later one would have been more faded, but it's actually gotten darker. Could it just be that I need to wait it out or could I have gotten pregnant again that quickly?! Thanks :)