Suggest Tests To Determine The Father Of The Child

Hi , I Had A One Night Stand Unprotected Sex Last Month On The 14 Which Was Also The Day If My Last Period , I Had Gotten Back With My Bf & Had Sex With Him On The 21st & Further On The Rest Of The Time I Am Now Pregnant & Not So Sure Of Who The Father Is I Have Looked Up On The Internet The Reverse Conception Calculator Due Date & It Says I'm Due September 16 & I Most Likely Conceived On the 24 Which Was My Ovulation Day