Thanks for the query.
Premenstrual spotting is indicating hormonal
After stopping the contraceptive
pills it may take some time for regularization of the cycles.
This may vary from person to person.
Some women may get normal period after one month of stopping the pills and some women may need few months to get normal cycles.
Contents of contraceptive pills may be in your system now but the hormonal imbalance due to the usage of pills may be persisting.
If you are having ovulation regularly, this spotting may not prevent the pregnancy
But better to get evaluated.
Consult gynecologist once, get examined and go for ultrasound
Then with her advice you can go for hormonal profile including estrogen, progesterone
, LH and FSH.
If she suggests go for thyroid profile also.
With this workup the possible cause for your problem can be identified and treated.