How can you tell if it was implantation or a regular period? paternity in question?

my bf and i broke up and a few weeks later a friend of mine and i started seeing eachother and were together for about 2 weeks and everytime we slept together it was protected...until the last day when it broke. the first time we had sex was july 15 and the last was july 27th but my ex and i decided to work things out and we were together on july 30. i got my period on time on august 2nd and lasted til the 5th which i've always had short cycles. about 3 weeks later i took a test and it was negative. a week later i took another one and it was positive on september 2nd. when my son was born he was 9 days early. i see more of my boyfriend in my son but then again im not too sure cuz my son looks just like me with little features that are different. im caucasian and my bf is puerto rican but the other guy is venezuelan/peruvian so its hard to tell. any answers on date match ups and who is most likely the dad?????????????