Confused lang po need q po ng advice?

Regular na last menstruation q eh nung oct 11 2019 wait q ung regla q ng nov 11 ngkaroon nmn aq pero isang araw lang madami din pero nwala din knagabihan kaya dq masabi qng last mens q is oct 11 or nov 11..? Pa help nmn qng cno nkaranas ng ganito kc dq alam qng 6 months nqng buntis o 7 months na..? Pls pa help kc d pq nkakapag ultrasound at check up gsto q ma cgurado lang qng ilang buwang buntis ba tlga aq??