Please help.Could I be Pregnant?

I was due my period on May 28th but because I already had a period in May I expected to be a few days late as we all know nature has a habit of making sure we don't often have two periods in the month. Trouble is I'm a week and a day late with extremely sore enlarged breasts and a swollen tummy. I've been having twinges of pain but nothing like I normally would and I don't have any other signs. My head usually messes up when I'm nearly due and that has happened but it's mostly gone now and I've not had any of my other usual symptoms such as chocolate cravings and extreme thirst although I'm very tired. I've only ever been naturally late 6 days. The only other time I was very late I had taken the Morning After Pill and that was what messed up my cycle. So do you guys think I'm over-reacting or should I take a Pregnancy Test?