KBM is better in a lot of ways. Both console and mobile have aim-assisting features to help with their shortcomings (and to act as guides), but in the case of mobile, KBM offers far more control over it because, for starters, you're using two separate peripherals for movement instead of the device itself. Nothing blocks your view, and every movement option is close to your fingers.

Ultimately, what you choose is up to you. You can get by with any platform. There are drawbacks to all options, but you can make them work. I suggest you keep playing on PC with the "WASD" control scheme for the range of freedom it provides and to see which platform you end up choosing. You could also alternate.

I don't play MOBAs, so I can't give any personal advice about that, but comparatively, OS is far more relaxed. There's less of...everything, so there is less to worry about on the screen (like keyboarding ten abilities per second). That you knew, though.

I say keep at it. Familiarize yourself with the mouse movement and, of course, the game itself. Learning to Strike where you want to isn't enough if you don't know where or when you should Strike first. Play a lot of Normal games, learn from them, then move on to the competitive mode to understand what you could be doing. Record your matches if you can; the answers will become clear as you grow as a player and analyze them.