Miscarried without knowing I was pregnant - Using Evra?

I started using Evra on 26th Jan, 2 weeks before my period was due. My bf and I bin 2gether 2 n half years and we bin using withdrawal method for 18 months with no pregnancy. On 5th Feb (when period was due) I had some brown smudging (barely nething). That stopped after 4 days. On Sat (16th Feb) I was starting my patch free week. I took the patch off and half hour after that I began to have the brown smudging again.(In booklet it said up to 4 days before coming on). Yesterday (Mon) about 3.30pm, I felt something slip out of me, thinking it was a large gloop of blood (normal for me after sitting for a while), i went to the loo to discover a greyish sac on the pad. It was bigger than a 50p and on touching it was quite firm with something red inside. Ive been having strong stomach and back cramps and bleeding a lot since. Was this a miscarriage? i didnt even KNOW i was pregnant and we werent trying. HELP!