If you are using Dynamic Difficulty turn it off and go with a straight setting like Veteran, All-Star or HoF (if new I suggest Veteran as you will see breaking pitches and not every pitch down the middle) Dynamic will mess with your hitting, drop your difficulty, then you mash, then it raises it, and you can't hit for [censored] etc..
Right now the only way to boost your power numbers is to use equipment as training is....sparse... to say kindly
You can use Normal and Contact swing and still hit homers, power swing use very sparingly unless you know that you're getting a pitch in a spot for sure. (I only use it if I know that a pitcher is gonna pitch me in a certain spot and I am ahead in the count) Some pitchers you can read, like they will pitch twice in the lower zone, one outside then come in on you.....I ambushed a few this way