What Causes Delayed Periods And Cramping In Vaginal Area?

I stopped taking BC (birth control) pills at the end of August 2015 after being on them for about 7-8 years. I had my normal period a week after stopping them right on time and normal. I then didn t get my period for another 3.5 months, which took longer than expected, but Doctor said not to be too concerned and that it was the result of my hormones getting back to normal. This period was normal and lasted 5 days. After that period, I had a blood test done and all my fertility hormones came back good (according to my doctor). Now its been 46 days since that period ended (counting it as cycle day 51) and I have had cramping in my vaginal area, as well as my pelvic area. I am getting an ultrasound done in the next month, and I am not pregnant due to negative tests. What I want to know: 1) Could these pains I am feeling be from ovarian cysts? 2) Could they be from my body preparing for a very late period like the first time? 3) How long is classified as normal for a period to regulate normally again (28-30 days) when you had regular periods prior to taking the pill?