I understand your worry.
If you do not intend to get pregnant, you need to use a condom or use a contraceptive
pill or refrain from sexual intercourse.
USG for RPOC is ultrasound
scanning of the uterus done to check for any retained products of conception. Please get it done.
You need to wait until your next menstruation
to happen to confirm if you are pregnant or not.
Always practice safe sex or use a effective contraceptive measure to prevent pregnancy
Be wise and take good decision favoring you.