Plan B?:/

So I ended up having unprotected sex with an old friends with benefits guy , and he only pulled out once , the rest of the times he didn't .  I thought I was nowhere near my ovulation period (the green days on this app) but I was actually one day away from those days.  Should I take plan B to be safe? If I have to I would , but I don't like it messing my period cycle since that usually happens :0