Anxious need advice

I’m trying to relax but my pregnancy tests aren’t getting darker in fact maybe lighter I’m 5 weeks today had a blood test at 4weeks 5days hcg was 42 she said was low but still early so I go back Monday for another blood test I’m even more nervous because I’ve been spotting dark brown, pink, and sometimes dark rusty red ONLY when I wipe that’s it I’m so scared my baby is leaving me but I’m trying so hard to stay calm it could be nothing it could be because of my endometriosis or it could be something has this happened to anyone?