Luckily for you if you’re kept in a belt what you think doesn’t matter any more, does it? You’re belted and denied. All that matters is what he thinks, as he has the key.
Personally I think it’s better for you to learn the self control and submission to not even need the belt, so I’d recommend your boyfriend gives you those opportunities.
As for saving your virginity for your wedding night, I think it’s wonderful. It’s actually exactly what I did with my wife. I introduced her to denial when we were dating, as she was shy and her background meant she’d barely even masturbated when we met. Once I taught her how good orgasms were I of course denied her, in order to completely let her inner slut out. She was sucking cock like a pro within months, had lost all sexual inhibitions within a year, and by the time we were married was so excited to have sex that I’m not quite sure how I survived our honeymoon.
18 years in and she still asks for permission to cum, and I still mostly say ‘no’, and she loves it.
Good luck with your journey, it sounds like an excellent start.