Yes, you have the possibility of being pregnant since you had unprotected intercourse
during the fertile period of your cycle. Please get a HPT after 3-7 days of the missed period with a fresh early morning sample of urine; else, you can get an assessment of the serum beta-hCG
titres now for an earlier ad better confirmation. If positive, it is likely that the bleeding you had could be due to implantation
, else, it could be an early period perhaps due to some transient hormone imbalance
. Hope this helps.