Scared to ride

So I've only recently lost my virginity it's been about 5 months now and he constantly acts me to get on top an I've only ever done it maybe once successfully, he gets frustrated because it's his favorite position but I feel that if I get on top I will crush him an he won't find me attractive anymore. I'm so lost on what to do i really LOVE sex but I wanna be more active an freely enjoy myself without feeling self conscious. Any advice