Positive or evaporated

Took this yesterday morning but I only saw the first line n I just left on the my sink I left for a couple of hours and when I went to the bathroom I saw the line I know mostly likely it's a evaporated line I just don't know my cycle I had a baby 6 months ago n I had the iud for only 4 month until me and my husband decided to start trying again so my baby's can be close in age !! We been having unprotected sex every since I got the iud off i been experiencing lower back pain idk when I'll start my period so I just want to see opinions