Just over 4 weeks ago I unfortunately had a miscarriage at 7.5 weeks. I bled for about a week and my HCG levels dropped to 494 by the time I stopped bleeding. The last week I have been feeling a little tired, emotional etc so I had some bloods done to check everything was ok. My HCG level came back as 18 on 15.5.15. Today I had a small bit of cramping and some brown discharge when wiping (TMI, sorry) and decided to take a pregnancy test. To my surprise a faint positive came up but I'm well aware it could be left over hormones. What is confusing is that I thought home pregnancy tests only picked up 20 or higher surely not 18 or potentially lower now as its 3 days after my test.
Any help would be appreciated. Thanks