I don't understand

Sabi • Baby girl born 12/12/12. ttc baby #2. Baby dust to everyone!
Hi guys! So I my period was 8 days late this cycle putting me at CD38. I decided to take a HPT on CD38 and it came back with a faint positive. I used the first response early pregnancy test. I was so excited i started crying because we have been trying to have another baby for the past year. Then the next morning on CD39 my period started!!!! Took another test to make sure I'm still pregnant and it came back NEGATIVE! I'm assuming another chemical pregnancy again for me.