Thanks for the query.
The possible causes for your spotting are :
- Post coital bleeding. Sometimes abrasions or tears due to intercourse can lead to spotting for few days.
-Ovulatory bleeding. According to your last menstrual period, the spotting you had could be ovulatory bleeding also.
-Rarely in case of early ovulation, that could be implantation
imbalance leading to intermenstrual spotting.
So, wait till your expected date of periods.
If you get the periods as expected, no need to worry.
If you do not get the periods on around the expected date, go for pregnancy