Can Coming Off The Pill Cause Delayed Periods?

I went off the pill three months ago and since I have experienced two regular cycles-the first was 35 days since the first day of my last period, and the second was 28 days. I was on the pill for 7 years, but prior to the pill I was always regular and actually, had very short cycles (usually 20-24 days). This month I am on day 37 and have taken a HPT which came back negative. I am also experiencing pain on the left side- somewhat dull, but fairly constant for a couple days now. What do you think?