I'm on day 33 of my latest menstrual cycle. This would be only my second period after my first child and 7 mths of BF. I know periods can be all over the shop and the fact that i was regular as clockwork (28 days) pre-baby is not relevant but i am having all the classic PMS symptoms, backache, headache, even a bit of nausea but no blood.....Should i be buying a pregnancy test?