7 month old is below percentile charts. Should I see GP or health visitor?

[TeaAndMuffins]

My baby had some weight issues for a while. He was born around 9th percentile, dropped to 0.4th and we were referred to the Infant Feeding team. When his weight stabilised again and the team discharged us, I relaxed and stopped getting him regularly weighed. Recently I felt like my supply was dropping and noticed he was much smaller than his peers, so I weighed him myself and it says he is just 6.3kg. This puts him below the percentile charts by quite a way I think. I'm feeling so so anxious and guilty that I didn't notice sooner and that I didn't get him weighed since we were discharged.
My question is, if you've had a similar experience, do you think I should take him to the GP or to the health visitor? Who is likely to be more helpful at this stage? And what are they likely to suggest?
I also have some deep-seated paranoia that they might think I've been neglecting him because of his low weight and remove him from me. If anyone can put my mind at ease on this I would really appreciate it.

Since weighing him myself yesterday, I've been feeding him like every 2-3 hours, including at night, with formula and breast milk. And trying to give him high fat foods. He's an extremely active and cheerful baby, just very small. I just feel so anxious and guilty it's making me almost constantly nauseous.

How does he look in himself OP? Is he content? Does he look gaunt or skinny or healthy? What’s his skin colour like?

Our baby was nearly 4kgs born and got weighed this week as bang on 8kgs at 10m so your son’s weight doesn’t sound really low to me to be honest.

Definitely give the HV a call though and explain the situation. I mentioned it to our HV when DD was 9m and she just said to go and get baby weighed in a month but that she otherwise looked healthy and they’d only be concerned if she had dropped 2 percentile lines.

He actually loves food. Unfortunately he's allergic to nuts so can't have peanut butter. He won't let me spoon feed him so I can't pack lots of calorific stuff into him - he likes to feed himself, which is great, but means less goes down. I think he's just extremely active so burns loads of calories, and hasn't been getting long enough milk feeds, which is my fault.

Definitely take them to the health visitor. You're not going to be in trouble for neglect by taking them to get medical help. If anything, that shows you're being a great parent.

How did you weigh him? My daughter was about 9-10kg before the number by difference weighing her on the scales with and without me corresponded to the value on medical scales. She's 5 now and 16kg and there can still be 0.3+kg difference between medical scales and scales at home which can make quite a difference when they are tiny

I'd start with HV and see if you can get a weight and length check next week then see the Dr if the weight is a concern.

My daughter had weight issues between 7 and 12 months and my HV said this is quite common as their appetite doesn't keep pace with their activity levels. It takes a lot of energy to learn how to move and make noise. My daughter only gained 200g between 7 and 12 months. She was really slow to wean and at 10 months when we switched to formula was almost solely milk fed still. It was only when she started having 3 meals and the same amount of formula that she started gaining weight. At 12 months she was still have 25+ Oz of formula a day. She was 20 months before she ate enough to reduce formula. She has a bunch of allergies so weaning was a challenge too but meant we had dietician and paediatric involvement which was reassuring.

Even if the weight is following his 0.4th line I would probably ask for a dietician referral to help ensure you find the right balance of foods and milk for his activities and you have a solid plan in place over the next 6-12 months as you transition from a milk to a food based diet for him.

For a bit a reassurance my sister was under the 0.4th percentile until 1 and on it until 2 before climbing to 50th percentile. I was always around the 2nd percentile and my little sister was average. As adults we are all pretty much the same size we are all within a dress size of own another and between 5ft2 and 5ft4!