No, pregnancy cannot occur if there is no vaginal penetration, irrespective of whether you are on your period or not. Without penetration, sperms will never reach the egg.
Degree in Biochemistry and Molecular Biology from the University of the Basque Country (UPV/EHU). Master's Degree in Human Assisted Reproduction from the Complutense University of Madrid (UCM). Certificate of University Expert in Genetic Diagnosis Techniques from the University of Valencia (UV).