Feeling low....

I'm 12DPO, period due on Saturday, woke up feeling excited & anxious about taking a pregnancy test, but thought even if it's negative might be to early.  Was negative.  Still was hopefully.  The AF comes this afternoon... Badly... Maybe because I do have AF that I'm super emotional... I feel helpless.  I young 27, eat well, excerise daily, don't smoke, don't drink... Sorry just feeling sorry for myself today... Not usually like this...