Yes you can plan your pregnancy as doxycycline half life that duration of elimination from body is @22 hours since it's 10 days it's safe.
However you should avoid using any Medicines then on, unless adviced by your doctor as during first 3 months of pregnancy its not safe to take any medications, particularly you should not take Doxycycline.
Next Steps
Consult her Gynaecologist
Health Tips
Any Medicines to be avoided during first 3 months of pregnancy.