Hi Lisa,

Thanks for contacting the UNH Yard & Garden Infoline about your apples. The following research was conducted by Master Gardener/Education Center Volunteer, Catherine:

For this year, I would follow the general pruning practices making sure at this later date to watch for and avoid buds if possible. It's likely with the warmer temps, your apples are starting to bud. " Simply following the “three Ds” of pruning will take you a long way. Prune out anything that is dead, damaged or diseased. To go one step further, prune out branches that cross over and rub the bark of one another." This is always a good idea every year so yes, I would do this even though you have pruned heavily in past years. If you still feel like you can safely prune more of the tree, I'd then head to the water sprouts you mentioned. Follow the prune no more than a third of the tree at one time rule of thumb.

As for fertilizing, I'm wondering when you last tested your soil in the orchard? Do you feel confident the pH is correct and the nutrients are balanced? If not, you might consider a soil test: unh extension soil testing - Search You might or might not be aware that much of NH tests high for Phosphorus so it might be good to know what your levels are so you can adjust your fertilizer if needed.

Otherwise, I can share this from one of our resource pages:

Fertilizing Fruit Trees
*The following section refers to newly planted trees, we can still recommend testing your soil however to see how the current makeup is and if/how you may need to amend soil!

Before planting fruit trees, we recommend that gardeners test their soil before planting to determine the amount of lime and fertilizers needed. Soil testing can be done through a number of private and public labs. UNH Cooperative Extension offers this service. Forms and instructions are available on our website, or you can call our Info Line at 1-877-EXT-GROW (<personal data hidden>).

Here are a few resources for you to reference: 
https://extension.unh.edu/resource/growing-fruits-care-mature-backyard-apple-trees-fact-sheet - this resource highlights thinning crops to ensure that fruit tree bears fruit each year

https://extension.unh.edu/resource/growing-fruit-training-and-pruning-young-apple-and-pear-trees-fact-sheet

https://extension.unh.edu/resource/growing-fruits-low-input-tree-fruits-nh-home-orchards-fact-sheet-0

https://extension.unh.edu/resource/fertilizing-fruit-trees

Best of luck!