It reads like you're doing all the right things. I wouldn't worry too much.
I found in most new "types" of flying, there was an adjustment period. For context I went night freight - Biz/GA - Airline over about a 10 year period and each time I found there were peaks & troughs in my mood & fatigue, almost exactly at the point you're at now, 8 - 16 months in. My theory is its a bit of your body & mind adapting to new conditions & partly a tension release after converting to a new type, new company etc. In my case it lasted about 6 months, then passed.
Keep doing what you're doing, ride it out, and I think you'll be fine. If it does get too much on particular days, use your companies FRMS and report fatigued.