Thanks for your query.
Being on birth control can cause irregular cycles and irregular bleeding.
itself is associated with abnormal cycles.
If your first pregnancy
has proved that urine pregnancy tests are unreliable, please visit a gynecologist at the earliest.
You need to be investigated thoroughly for PCOS, as it can lead to problems in periods and conception, if you are planning a pregnancy.
You might need medications to regulate your cycles/ improve fertility
Meanwhile, weight loss
is the mainstay of treatment, so please aim for that.