Have nothing much new to add, except still agree with all of the below.
Congratulations on your baby as well.
Should also let you know that my DS was very similar, except that his crying/screaming/hungry signs were there pretty much since he was born. The midwives in hospital were telling me to give him "top-ups", even though they could see that I had colostrum, and then milk. Yes, family members and doctors chimed in as well to say he should be on formula.
Well, he regained his birthweight fine (was on 50th centile), then tailed off a bit (dropped to 9th / 25th centile) and is now steadily on 25th centile. Has been consistently solely breastfed (apart from a couple of times when I was nervous enough to try the formula).
He did have very bad colic, which thankfully lasted only a few weeks, and then reflux, which I assume was another cause of his crying. And he can't tolerate milk proteins so I had to stop eating dairy. I tried many things - some colic remedies, a cranial osteopath, my GP, a gastroenterologist. Luckily, has pretty much sorted itself out now and he is a totally different baby (well, the same one actually, but ykwim)..
One thing I am sure of (and luckily, apart from the early suggetions of fomula, i have had the support of doctors and HVs since then) is that I am absolutely sure I did and am doing the right thing by continuing to solely breastfeed. For one thing, the formula surely would have made my DS worse as they contain cow's milk.
Suffice it to say - all babies are different, and you won't know what exactly is the problem with yours, but it's unlikely to be that you don't have enough milk if he is putting on weight, not drastically dropping centiles, and is producing lots of wet and dirty nappies.
Actually makes me quite angry to read that they are saying this to you.