Thanks for your query.
If you had penetrative sex, and ejaculation occurred during this time, then there are chances of preganncy.
You have not mentioned the date of your last normal menstrual period.
Also, you mention that this ' period ' is less and scanty in comparison to normal ones.
Since the bleeding pattern is erratic, you should rule out pregnancy
However, i need to know when was your last period, in order to opine if this is a normal period or not.
In the absence of any further information, it is difficult to comment.
Also, an emergency contraceptive pill
can be taken within 72 hours of unprotected sex to reduce your chances of conceiving, but this will further lead to irregular periods
stay protected for the rest of your cycle.