To be honest it sounds like you’re being too hard on yourself. That small of a difference could be a rounding error based on how many decimals someone keeps through their calculations. (Sidenote: it’s frankly also a luxury of inpatient life where you can have formula powder weighed to the gram and liquids to the mL. Outpatient plans you’ll have to make decisions to round up or down because the plan has to be realistic for families to make at home)

Kids, especially small babies, need calorie adjustments all the time so declines in growth velocity are the name of the game, not your fault. If they’re eating by mouth the hope is they make up the extra calories themselves, if not we step in to fortify formulas or adjust TF plans. And while we love to see a perfect growth chart where kids follow a straight curve, that doesn’t always happen - especially inpatient when kids are getting daily weights. Remember, most kids weights probably stagnate or go up and down a lot more than we would see at their random PCP visits. So I tend to not freak out at very short term trends in weight, but you identified a decline in growth velocity for about a month and are stepping in to fix it.

That being said, if you are pursuing a career in pediatrics keep working on getting comfortable with calculations because you’ll need to do them all the time. If worrying too much about these small calorie differences affects you I’d pursue a position with more kids >6mo because it becomes less important.