Ttc please help

Rebecca • I`m happily married with one amazing little boy and ttc with #2
So I'm just curious I'm on cd 27 and 13 dpo and I took a pregnancy test yesterday at night not with my first pee and it said bfn but my boobs are so painful exactly how they were when I found out I was prego with my son.  Is there a chance it's a false negative if it's not my first pee of the day