I got my periods only for 7-8 hrs.

Well I had my last proper periods on 15 march to 18 march then on 22-23 March i had inter course with my partner well protected but just once there was a penetration without condom only in the Starting for like few seconds. So I got some doubts And then on 24 march I took unwanted 72. And on 1 April to 3 of April I had this brown blood bleeding (like periods but blood was dark in color. And after that there was a lot of itching and burning in my vaginal area (due to side effects of the pill) for the whole month. But then on 1 may I started bleeding (I think it was my period bleeding) but it only lasted for 7-8 hrs and the blood was reddish and every thin. After that No spotting were shown so after 1 week I took pregnancy test (as my husband suggest to be sure that wasn't implantation bleeding) the results were negative and then after 4 day I again took a test which was also negative. Do you think that 7 hrs bleeding was only due to hormonal issues..? And my next periods willbe normal?