Are you sure your HV didn't mean 2x at night?
Frankly I would be knackered if my DS was feeding 6-8 times a night I would be knackered. The problem with calling it 'demand feeding' is that people think you need to wait for your baby to 'demand' to be fed when really its you that should be offering the breast regularly whether it's demanded or not. 'Dont offer, don't refuse' (Dr Sears/Kellymom adage?), to restrict the breast until it is demanded is a form of mother-led weaning.
You say he is distracted during the day, why, by what? (not having a go but do you spend much time on the sofa, brew in hand, chilling out and Bfing like I do?!) Are you making time, quiet time, for him to have some good feeds during the day? Sometimes you do have to do a bit of closet bfing. It might be worth having a few allocated 'quiet times' during the day so he can feed well.
I practise, I prefer to call it, ecological bfing and co-sleep but not a hippy as I don't like lentils. My DS is 8 months, 50th percentile for weight. I offer the breast very regularly during the day and he sleeps all night with 2/3 short dream feeds. He take food from family meals but not enough to really provide much sustenance. I really feel if you address the day feeding, he will sleep better.
His weight, IMO, is not an issue. I would focus more on developmental milestones, is he babbling, sitting unaided, starting to become mobile? (this varies, mine is crawling and can pull up to stand but is earlier than my DD was).