I don't understand why a baby that should be onto a good few solids by now, would need breastfed every 3 hours?
Surely there's an introduction of 3 meals a day by 9 months so it would be more a morning, afternoon and evening feed now? So she's telling you to feed him every 3 hours instead of getting you to focus on his diet and what foods he's eating?
Milk is their main source of nutrition until a year but from 6 months to 1 year old, there should be a steady increase in food and decline in milk. Being 9 months and half way through the weaning process, I would imagine she should be encouraging you to get to 3 meals a day, reduce breastfeeding slightly and by a year, be on 3 meals, snacks, water and breastmilk for top ups morning and night?
That's just how I look at it. Maybe I'm wrong seeing it that way? Once they're 1, they should gain independence and be eating solid foods as the majority of their diet. If you continue to feed every 3 hours until he's 1, you'll end up with a baby who is 1 and too full up from 8 milk feeds a day to even be interested in food?
I actually think her advice is maybe what's causing the weight loss! She's encouraging you to basically just feed your baby milk 6 months beyond when food should be introduced and to the point (1 year) when it should be their main source of nutrition. As in solid, whole foods