Troubles with movement

Chelsea • QLD | Future Registered Nurse 👩🏼‍⚕️💉
When my boy and I have sex, I get on top but I kinda struggle moving in the way he wants me to. He says he just clenches his arse to thrust but I have to physically move up and down where boys move back and forth. Does anyone else have this problem? 
How can I be better on top while being comfortable?