I've heard that relying on/boosting your mids (and potentially, dare I say it, turning down the bass a little) can help when playing live. I've had some success experimenting with that in live settings.
That of course depends on the frequencies your bandmates are dishing out. As was said, if your guitarist has a lot of low end, or if the drums are really deep and have a lot of attack, you may have trouble bringing out the bass.
I've played some hard rock in the past, with a guitarist and drummer who both had fairly ordinary tone for their instruments (in terms of low end). I played a Stingray H out of an Ampeg 4x10 cab. I was much less sound savvy back then, but I remember being pretty satisfied just rolling up the high end. Using the bridge pickup (or a blend) on the HH might be helpful too, if you're not already doing that.
Sometimes simple positioning can have a lot to do with how well our sound comes out, or at least how well you perceive your sound. Maybe move your amp around or stand in different places to see what helps. Putting your amp up against or closer to a wall emphasizes the bass more.
If none of that works, you could ask your bandmates to turn down just a little. I realize that's a delicate matter, but it could potentially help round out the sound for everyone.