Hi there you can't get pregnant from precut and certainly not from fooling around, your doctor goes by the last day of your period so if they say uou are 6 weeks you are only actually 4, I worked out I was due the 19th July every time I have a scan the date moves forward, I am now due the 14th July, the baby is your boyfriends with out a doubt x
You 110% CAN get pregnant from pre ***. That's why the pull out method does NOT work. In your case it is unlikely that you got pregnant from messing around and the baby is most likely your boyfriends. I would get a dna test after the baby is born to confirm he is the father but I wouldn't stress too much.
You can get pregnant from precum but not hours before your period. You have to be at a fertile time in your cycle.