maybe a dumb question

i suffered a miscarriage last month. i found out i was pregnant at 12dpo and it had me at 3 weeks 3 days and i ended up miscarrying at exactly 4 weeks.

if i was pregnant this month wouldn’t i be able to get a positive being 3 weeks and however many days again? or is it just based off implantation ?

my period is due tuesday but at 11dpo (yesterday) i had a stabbing like pain in my ovaries

tested today at 12dpo with fmu and got a negative but now currently having the same type of stabbing pain in my right ovarie again ?