so I lightly bled (like didn't even need a panty liner bled) July 22-30th. was supposed to start AF on the 20th but then

had a little smudge of pink like a dot on toliet paper when I wiped once. then wiped again, nothing. And this happened on the 18th of August and had no bleeding or sign of AF since.. And today took two pregnancy test and both were negative ..any ideas ?