try bigger tablet or lower dpi on mouse, go beyond what you have tried. chances are you haven't even tried oversized area on your current tablet. lower dpi on mouse might require a bigger pad tho.
Also, you've not played that much yet. You can more than triple your total standard playtime in a month with 1h/day.
try playing more without hd, so you can see misaim before you click better, maybe. whenever you click and your aim is off (even if you hit the circle) it can be useful to see it and try to aim better.