Thanks for your query.
It is most likely that the irregular and early cycle is due to the birth control.
With long term use, it is common to have erratic bleeding now and then.
However, even though birth control pills are almost 99 % effective in preventing a pregnancy
, the theoretical risk of a pregnancy definitely does exist.
Please take a urine pregnancy test to rule out this possibility.
Do mention the occurrence to your health care provider , in case you are not pregnant.