this sounds excellent advice...and can I just plead with you not to, if you possibly can, let the health visitor get you down by making/allowing you to think you're doing something wrong. Your hv might be a lovely caring encouraging person; here's a cautionary tale about mine though.
My dd hadn't regained her birthweight at two weeks. She was doing tiny gains but not apparently enough. At the first baby clinic, in front of all the other mums, the HV turned to me and said very loudly: "I think it's time you went home and started the hard work, don't you?"
This was two weeks to the day since my Caesarean. To say I was shattered was an understatement. I'd been feeding twice at night, five times during the day, lots of poos and wees etc. My milk had taken a week to come through and it was all agony.
still the hv made me come to clinic (knowing I'd have to walk there) even though I hadn't had nearly enough MW visits at home. I'd put on a dab of mascara - terrified she'd have me down as a non-coping mother - and I could see her looking searchingly at my face thinking i was spending more time on my appearance than feeding my baby! "Start the hard work"???? Oh right, because I'd been lolling on a hammock sipping margaritas.
So of course I burst into noisy, nose-running, full-on, in-public tears. I felt devastated and a complete failure. She was urging me into top-up formula. She turned to someone else's lusty baby lying on the scales and said: "Look, this is what you can achieve in another week!" Stupid crap comparison, frankly, as the other baby's mum pointed out: her ds weighed 9lbs at birth whereas my dd was only 6lb 10oz. Plus her ds was five weeks old!
Now looking back I can laugh ruefully - and i've never been back to that hv's clinic: always avoided her. Plus put in a semi-official complaint to the GP.
At the time, I wept, and I gave dd a formula top-up once a day in the evening. Now i'm really pissed off that I did it, - dd is now back to being excl bf. It did give me a bit more peace of mind, admittedly, but I think if I'd had better advice such as that from tiktok I would have been able to carry on bf exclusively and achieve the right weight gain.
By week three, by the way, dd was back at birth weight and is now on 50th centile at 5 months.
Good luck with it all and try to relax.