Your hormones might be causing the problem but there is nothing stopping you from rising above that. It sounds to me like you need a goal, a strong reason to keep trying to LD.
You say that your dreams are uninteresting and meaningless. With no goals or intent your subconscious takes over and tries to make them as exciting as possible, by filling them with sex. When you first started lucid dreaming your dreams were exciting because lucid dreaming was new to you, now you’ve run out of things to do and it all feels a little ordinary.
Hopefully that’s at least somewhat close to how you feel.
I think you should try to be more ambitious. Set yourself a goal, something you want to see or do. Don’t make it something dull either, make it something that will push you. Because you can do anything you can imagine in a dream.
The big lucid dreaming to-do topic might give you some ideas to build upon.
When I learned to lucid dream my goals were ambiguous and my dreams reflected that. When I set a clear goal for myself I achieved lucidity fairly easily. I’m always building on my goals to try and keep things interesting and it seems to be working for me.