Hi Mine Are Irregular Periods From Starting. Now I Want

hi mine are irregular periods from starting. now i want a baby. my last period is on 18th june 2015. i went to doctor for advice and she told me that to do preg test once again on 9th july if it comes -ve use regestrone 5mg tabs for 1 week. on 8th july i found spotting and it lasts just for few mins or seconds. i thaought that my period has started and i am using regestrone 5mg and progynova 2mg as doc suggested me to take for 14 days as my periods started. as i found spotting only i did my UPT on 11th of july and it came -ve. i am still on using these tabs because i am not sure that i am pregnant are not.

now my question is is that period bleeding or implantation bleeding. when i have to test exactly. whether these tabs i am using wont effect my pregnancy if i am pregnant?