When will be the next period?

I’ve been using Diane 35 for almost 8 years. This January 2011, I bought a box of my Diane but my boyfriend suddenly proposed and he wants us to get married and have a baby right away. I stopped taking Diane immediately, I was only able to consume 10 tabs (10days). I have a regular period ever since, 28 days cycle. I’m 2 days delayed now, i bought a pregnancy kit but I was negative. Is this because I did not finish my Diane? When will I have my next period?