Knowing when to feed (especially when formula fed)

This feels like a stupid question. At one point, we were probably way over feeding our (formula-fed) LO, because any time he cried/seemed unhappy, we assumed he was hungry. So he was eating way more than expected for his weight. Well, we corrected that, to try everything else it could be first.

But last few days he seems genuinely hungry. He is 6 weeks, roughly 10lb. (So, he should be eating approx 25oz/day.) Our "minimum" is 3 hours between (4oz) feedings, with some longer stretches if he's sleeping, but it seems like he is hungry again after just 2 hours. Making mouth motions, chewing hands, rooting. I don't think we're misreading the signs... And a pacifier won't soothe.

I guess what I'm asking is, how do you all tell when to feed? How much do you let a clock rule it vs baby, especially when you're not as well-versed as you'd like in reading baby's signs? I hate the idea that he's crying and hungry and thinking, "MOM! Why won't you feed me?!" but I don't want to be feeding him when he's not hungry, just to shut him up...

How do you tell when they might be in a growth spurt and legit need more?

I guess I just don't trust that I know how to read him :-(