Quick Question

Just a quick question. Please do not comment any hurtful comments. Me and my ex broke up last July and we met up once more on August 27th and ended up having sex. We didn't use protection but he did pull out. I got together with my current boyfriend, who I have known for over a year before we got together, two weeks after August 27th. We had unprotected sex all of September and October. I found out I am pregnant on October 21 and around 2 weeks along. My last period was September 18th. The doctor said I conceived around October 5th. I'm pretty sure that incident from August 27th wouldn't effect it and I'm 99.9% sure that this baby is my current boyfriend's but just for my own peace in mind what do y'all think?