being on top

Everytime he motions me to get on top I attempt to but I can't really get him in but when I do he won't stay in and there's not much to ride imo. He's not tiny or anything , he's average about 6inches but I guess I'm not coordinated. He looks disappointed when I can't do it properly and I know it's one of his favorite things from when I asked what positions he likes. And he thinks it's best for girls cuz a girl came from being on top with him before. Idek what I'm doing but I mean I definitely have the thigh power to do it (thick ass thighs 🙂). How can I make this process less awkward and more enjoyable for both of us? I dread it when it happens cuz I never do it right and he just slings me over on my stomach and starts doing the work cuz I'm not satisfying him on top lol