I always felt that "heavy" is all relative....
I lift 185lbs on bench press. That's not much.... but that's as much as I can do with good form, for an adequate number of reps. So to me, that's heavy....
I think you shouldn't worry about the numbers, just make sure you're pushing yourself as hard as you can with perfect form.... and if you fail between 6-10 reps, that's a heavy enough weight for you. There's some benefit to cheating a little bit for one or two last reps once you've reached positive failure, but be safe.