Tips for being on top

I have a really hard time enjoying myself while on top with my boyfriend. I've had great sex with exs in the past while being on top but I just don't feel confident anymore. 
I don't like him getting a full frontal view of me Bc I'm not as in shape as him. I've tried turning off lights, he lives with his parents so maybe that might be why I can't fully enjoy it Bc that's always on my mind.
I can only grind on his dick... Sounds weird but I don't know how to bounce on it properly like you're supposed to.
So if any ladies have any suggestions on helping build my stamina to last longer on top, grinding and bouncing tips or anything that I can try with my man next time I attempt to get back on top and spice things up is appreciated 😊