Usually nitrogen is the fertilizer element most important for growth promotion. Low P would only slow the growth if there were deficiency symptoms on the leaves. Why not increase P and N both next yr and see what happens.

I use 10-10-10 synthetic fert every year what should I increase N and K to?

Yes increase both. See what you can find like urea 46-0-0 or ammonium sulfate 21-0-0 and something like this potassium sulfate 0-0-50 https://www.amazon.com/Organic-Sulfate-Potash-0-0-50-pound/dp/B01CKDEQLI/ref=sr_1_20?s=lawn-garden&ie=UTF8&qid=1475088775&sr=1-20&keywords=potassium+fertilizers

Urea is good if your pH is low enough. Ammonium sulfate if pH is a bit on the high side.

I just looked potassium deficiency symptoms and I believe some of my trees have it, which would make sense since my soil has 10% of the optimum ppm for potassium. They have the brown leaf edges, no growth, and slightly yellow leaf veins. Which I thought was normal but I guess not.