Hello
Thanks for posting your query at DoctorSpring.com
Well, the second period that you had happened because you stopped the birth control after taking it for 6 days.
Your ovulation this month would be unpredictable, since this period was a withdrawal bled after the birth control stopped.
If you wish to plan a conception, it is much better to plan your ovulatory dates next month, after your next period, as that would be a natural period.
With a 35 day cycle, it is very difficult to predict the precise dates of ovulation, as ovulation can occur anytime from day 14 - day 22 of the cycle.
If you have been trying for longer than a year to conceive, it is best to undergo follicular monitoring via ultrasound scan, instead of using OPK kits, as they are quite unreliable in longer cycles.
Take care.
Please feel free to discuss further.
Regards.