Really long article can help to understand what could be driving high degradation:
https://cleantechnica.com/2016/05/31/ba ... ries-last/
More plain language chart from Nissan Leaf: https://insideevs.com/news/326563/batte ... ssan-leaf/
From the 2nd article, at 2 years, the Leaf should expect to have lost about 13% of battery capacity. At 2 years, sounds like you've lost 12%, but you have far less miles than the above chart assumes. So your degradation might be on the high side. Or it could be normal, especially if your usage cycle is on the harsh side. That 1st article covers a lot of things that impact this.
I'm no expert, I only have my personal experience to draw upon. My Leaf lost it's first of 12 capacity bars at just short of 6 years and about 37k miles. That capacity bar per the above article suggest I've lost 15%. But my Leaf lives a sheltered life. We rarely DC quick charge. It is in a moderate climate - rarely over 100F and never under 35F. Also, it is garaged and so rarely encounters those extremes. We normally charge it only to 80% except for the handful times a year we anticipate needing further range - usually for longer range trips we take the PHEV or other gas powered car. It has been to turtle mode only twice, and that was due to a malfunction that was repaired - so no deep cycling. It has pretty much lived it's entire life between 20-80% charge. I think our optimal treatment of the car has allowed us to experience better than normal degradation. So if your usage is listed as one of the practices that reduce battery life, do what you can to adjust those practices. From my limited experience, it would seem that can have a huge effect on the battery life.