Should a 15 Year old be able to date a 20 year old?

wellmy name is marie and im 15 and im dating a girl tht is 20 years old and we are in love but itz very difficult bekuz her mom nd my mom dont approve of it wll at first our momz were kool with me nd her hanging out until she tried to over dose because they tried to keep us from seeing each other about three weeks ago...bt now we do what ever it takes to see each other nd if yew knew how we felt about each other yew would do anything too...bt yea...thnx for yewr help (: