miscarriage? ectopic?

So on the 5th of september i got a positive opk

i tested 3 and 2 days before my period was due, both negative.

EXACTLY the day my period was to start (literally two weeks after positive opk) i experienced period like cramping for a few days and what looked and felt exactly like a normal period. regular bright red bleeding continued for about 4 days, no clots, and then it turned dark brown, and slowly got lighter, and i’ve been spotting on and off, sometimes lighter sometimes a tiny bit heavier. after two weeks of this i took a pregnancy test, blazing positive. bloodwork only showed my HCG at 140, nothing abnormal on ultrasound but no sign of pregnancy. i’m on week 3 now of spotting, it was brown and slowly tapering off but now it’s a pinky red again

i’m confused?

does this sound like an ectopic pregnancy?

i have very very mild pregnancy symptoms, mainly food aversions. no pain other than bad lower back pain in the middle but this could be due to moving furniture.

i just don’t understand how hcg was at 140 two weeks later unless it was rising slowly, because my test was negative before bleeding started. i’m terrified lol