Thanks for the query.
Birth control pills can cause menstrual irregularities like inter-menstrual spotting, delayed or absent periods etc.
So your symptoms can be because of this.
Usually pills should be started from the first day of the periods for complete protection. But as you started the pills on the 5th day and as the pills are having some amount of failure rate better to go for pregnancy
If you want the baby you have to stop the pills first, then after regularization the cycles plan intercourse around the time of ovulation.