My periods can be different sometimes. Mostly it will arrive without any spotting before or anything, and will be super heavy for the first 2-3 days then it will taper off and usually by day 5 it's gone or I may have some spotting at most. But then occasionally it will change and it will be shorter or will mostly be light to spotting without any pain or anything. It doesn't usually happen that way but I have had a few random periods like that.
I have had a couple of cycles where I have had faint positives before but then af arrived. I did have an early mc quite a few years ago, started as spotting but progressed quickly to full on bleeding which was much heavier than a normal period and was more painful, like waves of pain a little like mild contractions. That was at 8 weeks.
I don't know what's happening with you, but I hope it turns out to be positive news! I can see what you are seeing, but these tests can be so confusing at the best of times with their indents, evaps, super faint positives etc. If only digitals were a little more sensitive