period flow was minimal

so i had sex 22nd july, 26th july & 7th august. my last period was on 16th july. the cycle was normal but a week earlier than my due date. i started bleeding on 9th of august this time (again a week earlier) although it was minimal spotting. then on 10th of august i did bleed normally but on 11th of august, bleeding was minimal again and it has stopped completely today. is this a true period? i keep taking a pregnancy test every week but it's negative. last i took was 8th august. should i go to a gynae

extra information- recently started a job that requires a lot of travelling and i haven't been eating well.