Low weight and panicking

So my son is 3 months old and his growth chart keeps going down. He’s now in the 11th percentile for his height and age. I have plenty of milk and also tried formula, he just doesn’t want to eat as much as they want him to. He is 12 pounds right now and they think he needs to get a tongue tie release to help but it seems like they are just guessing and hoping that’s the issue. Do you think he’s just a small baby and totally fine? We bottle feeding because he won’t latch for long which I agree can be the tongue tie, however the tie isn’t significant (like only a slight tongue tie) so I’m not sure. He doesn’t seem hungry he’s very chill and happy except when he has gas like any other baby. Should I get his tongue released? Should I ask them to look for other reasons he could be under weight? Should I just let him be happy and weigh whatever as long as he’s thriving and not dangerously low? Opinions please !