We're struggling with reflux too. Baby girl is in the 3rd percentile for weight. Her pediatrician prescribed pepcid and that's been helping and she's been able to eat more and more frequently.
I don’t know if you’re formula or bf but this helped us right away; had to change my diet to pretty strictly chicken and rice or red meat and salad all from home with no seed oils or sauces, 95% water, drink one coffee with less than 100 mg caffeine no syrups or add ins. Super boring but it has helped his spit up so much he’s finally gaining at 8 weeks he’s in 25th percentile. I feel you tho don’t worry those babes are stronger than we think you’re doing great mama keep your chin up 😉 I only feed him upright or in the biological position (baby on belly) so he has to hold his head up and find the nipple himself.
You got this mama. I noticed my little one would chug her bottle way to quick in the beginning as well as this would cause her lots of reflux. Not saying that something as simple as changing what bottles you use will completely help with everything but it’s worth a try. I started mainly using the Dr Brown bottles in my daughter and I noticed her slowing down in her feeding and way less reflux I also tried to keep her upright for at least 15 min I hope this can be of help to you. These bottle force your little one to drink slower. https://amzn.to/4jjHL4y
You’re going a great job! All babies are different. Do you sit him up after he eats? We do that with our reflux baby it seems to help a bit.