Hi Schrodinger,
I commented on your first thread about your DS "eating too much" (and I think we've chatted on late pregnancy whinge threads in August!)
To recap, my DD is 9 weeks old now and I'm a first time mum too; she was born big at 9lb7 but was nearly two weeks late. My MW's and HV's told me that because she was so late, I effectively got a two week old baby straight out of the womb, and the amount she wanted to eat straightaway made sense, like she kicked into her 10 day growth spurt immediately (also the fact she was so alert from birth made sense for that too). I told you on your other thread that she was at 5 weeks - I assume in her growth spurt for that age - eating upwards of 40oz per day; she's now calmed that way down and is eating 25-30oz (not quite enough in my opinion for a 14lb baby, but I can't force it down her and she's following her centile lines perfectly).
So, following this logic, if your DS was two weeks early, he's in his 3 week growth spurt now; as he's 5 weeks old he could be hitting his 6 week old growth spurt, iyswim.
Your HV sounds like she came out of the ark, tbh - she's giving you advice that my mum was given 35 years ago when I was a baby (I've had these discussions with my mum about giving DD water, leaving her to cry, etc; which I've gently nodded and smiled at and then flagrantly ignored. However, this is much easier done with my mum, and not someone who is supoposed to know about these things like your HV.)
Schrodinger, you know your little boy, you're the one who's with him 24/7; not your HV. Is he producing wet nappies regularly? Is his poo soft (don't worry too much about getting dirty nappies every day, my DD has only just started that delight, although if he's going more than 3 days then that might be a concern)? Is he happy enough and alert while he's awake, and does feeding him make him happy? Then I would say that he's ok, maybe a bit of a fat knacker :) and that he's either trying to climb centiles or going through his growth spurts, or all of the above.
If he's screaming non-stop all the time, then yes, there may be an issue, and I would say take the advice about having him checked for reflux/other issues above.
Take him to your GP, just to put your mind at rest. When you call up for an appointment, tell the receptionist that you want to speak to a GP who is female and maybe a bit older. When you go for your appointment, make sure you take a list of all your questions and notes on your concerns (I've just done this at DD's 8 week check, and my GP was fantastic, sat down and listened to all I had to say and gave me considered answers).
Just because you are younger does not mean your opinion and instinct doesn't count. (And I have certainly never thought from any of your posts that you sounded 21 at all, more like me in my old age of mid-thirties!) Refuse to see this HV - just be out when she's coming. Can you take her to a drop-in clinic in your area instead? Don't let this woman make you obsess about his eating, as that way madness lies (believe me, I am utterly neurotic about DD's eating habits and amounts, but that's another story!).
I'm no expert on any of this sweetheart, I have one baby 4 weeks older than yours. But you completely sound to me like you're sorted and you know your little man; go with your gut.
Keep posting, and let us know how he's going. Just so you know, my DD hit 6 weeks and (it seemed like) stopped eating - she dropped her amounts right down. He may well do this.