How to retrieve nested JS object and get its data by index?

I have an extensive JS object with any nested objects, eg:

data = {
  sundriesIncreases {
    month1: { projectedIncrease: 1.3, actualIncrease: 1.3 },
    month2: { projectedIncrease: 1.6, actualIncrease: 1.5 },
    month3: { projectedIncrease: 1.4, actualIncrease: 1.4 },
    month4: { projectedIncrease: 2, actualIncrease: 2.1 },
    month5: { projectedIncrease: 1.2, actualIncrease: 1.3 },
    //etc
  },
  //etc
}

I am using a loop to loop through a different data set and I want to use the index of that loop to retrieve the corresponding months data from the array.

However, I am having trouble trying to figure out how to get a given value of the child array by index.

So far I have tried getting it by index as such:

customerNumbers.forEach((amt, index) => {
   let actInc = data.sundriesIncreases[index].actualIncrease;
   console.log(`amt=${val} index=${index} increase=${actInc}`)
});

And converting the parent object to an array:

var increasesArr = Object.entries(data.sundriesIncreases);
customerNumbers.forEach((amt, index) => {
   let actInc = increasesArr[index].actualIncrease;
   console.log(`amt=${val} index=${index} increase=${actInc}`)
});

But so far nothing works.

Of course

customerNumbers.forEach((amt, index) => {
   if (index == 0) {
     let actInc = data.sundriesIncreases.month1.actualIncrease;
     console.log(`amt=${val} index=${index} increase=${actInc}`)
   }
});

works, but this isn’t ideal.

Googling the problem reveals a lot on how to get the key by value noting a lot about how to do the opposite.

Would anyone be able to point me in the right direction?