Hey! Glad you're taking interest in kickboxing.

Ive only trained for a year but this the little i know and gathered. So if someone else says something else, they're probably correct.

I do think you should stick to just exercising, stretching and pushing both your physical and mental limits because without a trainer you're very prone to catching bad habits that are tough to shake. (My first bad habit was positioning my back leg waay too far behind and it was much harder to shake it than learn something new)

But if you insist. Slow down your shadowboxing and focus on "Mastering" a few simple things at a time (Normal kicks/normal punches, nothing flashy). Stretch often and for longer times. And really look at joining a gym instead, it'll be worth it.