Eight-week-old taking less formula and fewer wet nappies, should I worry?

[DoNotLoseHope]

Hi would love your guys opinion. Im a first time mum and my baby is now 8 weeks old. She started off as a really good drinker having 600 ml by the time she was 2 weeks. She felll of this by week 4. For a month now she’s been struggling with feeding. I’m stuck on 3 oz every 3 hours out of which she sometimes drinks 1, 2, 2.5 etc totalling around 450 ml a day sometimes lower or higher. On some days she has around 4 wet nappies rather than 6-8 range which also worries me.
my question is what do you think is going on with my baby?
She is formula fed and I do give her a little breast milk too which I cannot measure. But I know it doesn’t make up for the 100 ml that’s missing as it would show in the wetness of the nappies. I’m thinking maybe I should change her milk.🥛
she is also constipated and has some sort of reflux going on

Just to add I have already been to the Gp and spoken to health visitors and I don’t feel satisfied with the answers that’s why I’m turning to strangers on the internet

Have you tried changing the teat on the bottle to a faster flow?

@Jellybunny98 no because sometimes she chokes on the milk, keeps in her mouth before she swallows especially when sleepy. Do you reckon the teat might be tiring her out?

I think it’s worth a try. If she has to work too hard at the teat she may well just decide she can’t be bothered, it won’t hurt to have a go x

Try a variflow teat, if won't flow too fast, but will stop her working too hard, had a similar issue when my dc2 was tiny