You probably are getting there, the nitrite readings are fairly low, but still present
While the tank cycles, you'll probably want to change the water according to the tests, if the nitrites get high, don't worry about changing out a little more frequently than usual, it won't hurt anyone, and it will most likely help the fish a lot.
When it comes to beneficial bacteria, I use fluid filter medium by Easylife, cycled my tank in a week. And I've also had experience with stresszyme by API (I think?), you could check those out