I have been told - and note, I'm a denizen of this community, so I'm not actually good at this - that *when* you add the baking soda to the batter can have an effect on how fluffy the end result is, especially if you're slow with the mixing and measuring so it ends up sitting awhile. So if you didn't add the baking soda as the very last thing, maybe try that? (Adding it last gives it less time to react.)

If you think that maybe the recipe just makes for a fluffier bread than you'd prefer, then you can just reduce the amount of baking soda, too; but you'd have to either guess, or base it on a recipe you've made before that does come out to the right density.