What you have described could be either pregnancy or coming off the pill.
When you come off the pill you have a normal withdrawl bleed but when you have your first natural period depends on how quickly your body starts producing the hormones to start ovulation.
Some women are more fertile after stopping the pill so get pregnant straght away. Others have a period 4-6 weeks after stopping the pill and others dont have a period for a few months. Again this is based on your body and when it start ovulating again.
It can take a year for your body to get used to not being on the pill and cycles to completely regulate again. If your cycles were irregular before going on the pill the chances are they will be irregular now.
Take a pregnancy test if negative, repeat the test a week later. If both tests are negative then it's unlikely to be pregnancy related but not impossible.
It could just be your body readjusting to having to produce hormones naturally and not have the artificle ones pumped into it every day.
You might also experience hair loss 3-5 months after stopping the pill which lasts a month or two. This is due to a hormonal imbalance in your body and once the hormone leves are correct the hair loss stops and things settle down again.
Hope this helps.